In OpenERP first create custom module and inherits the hr module in your existing module.

Follow these step given below

Step1- First create existing module like as test and than create .py file in your own module like as a test.py file and this file pass in the __init__.py file.

Using this code given below

class product_product(osv.osv):   
    _inherit='product.product'
    _columns= {         
               'design':fields.char('Design', size=128, required=True),
               'dyes':fields.char('Dyes', size=128, required=True),
               'colour':fields.char('Colour', size=128, required=True),
               'min_price':fields.char('Min price', size=128, required=True),
               'market_value':fields.char('Market value', size=128),
               'supplier':fields.char('Supplier', size=128),
               'age':fields.char('Age', size=128, required=True),
               'm_length':fields.float('Size(M. Length)'),
               'm_width':fields.float('Size(M. Width)'),
               'f_length':fields.float('Size(F. Length)'),
               'f_width':fields.float('Size(F. Width)'),
               'origin':fields.many2one('res.country',"Origin", required=True),
                       
               }
    def update_descrp(self, cr, uid, ids, context=None):
        obj = self.pool.get('product.product')
        for val in self.browse(cr, uid, ids, context=context):
	    a1 = ''
	    if val.design:
		a1 = val.design	    
	    a2 = ''
            if val.origin:
                a2 = val.origin.name
            a5 = ''
	    if val.dyes:
		a5 = val.dyes
            a6 = ''
	    if val.colour:
		a6 = val.colour
            a7 = ''
	    if val.m_length:
		a7 = val.m_length
            a8 = ''
	    if val.m_width:
		a8 = val.m_width
            a9 = ''
	    if val.f_length:
		a9 = val.f_length
            a10 = ''
	    if val.f_width:
		a10 = val.f_width       	    
            description = 'Design' + ' : ' + str(a1) + '\n' + 'Origin' + ' : ' + str(a2) + '\n' + 'Material' + ' : ' + str(a4) + '\n' + 'Dyes' + ' : ' + str(a5) + '\n' + 'Colour' + ' : ' + str(a6) + '\n' + 'Size(M)' + ' : ' + str(a7) + 'x' + str(a8) + '\n' + 'Size(F)' + ' : ' + str(a9) + 'x' + str(a10)  
	    
            self.write(cr, uid, [val.id], {'description': description,})
        return True
    def create(self, cr, uid, vals, context=None):
	a1 = ''
	if vals.get('design'):
		a1 = vals.get('design')
	a2 = ''
	if vals.get('origin'):
        	aa = self.pool.get('res.country').browse(cr, uid, vals.get('origin'), context=context)
        	a2= aa.name
	a5 = ''
	if vals.get('dyes'):
		a5 = vals.get('dyes')
	a6 = ''
	if vals.get('colour'):
		a6 = vals.get('colour')
	a7 = ''
	if vals.get('m_length'):
		a7 = vals.get('m_length')
	a8 = ''
	if vals.get('m_width'):
		a8 = vals.get('m_width')
	a9 = ''
	if vals.get('f_length'):
		a9 = vals.get('f_length')
	a10 = ''
	if vals.get('f_width'):
		a10 = vals.get('f_width')
        if not vals.get('description'):
            vals['description'] = 'Design' + ' : ' + str(a1) + '\n' + 'Origin' + ' : ' + str(a2) + '\n' +'Material' + ' : ' + str(a4) + '\n' + 'Dyes' + ' : ' + str(a5) + '\n' + 'Colour' + ' : ' + str(a6) + '\n' + 'Size(M)' + ' : ' + str(a7) + 'x' + str(a8) + '\n' + 'Size(F)' + ' : ' + str(a9) + 'x' + str(a10) 
    
        return super(product_product, self).create(cr, uid, vals, context=context)

Step2- Then we create another .xml file like as a test.xml file in your own module and pass this file in the __openerp__.py file.

Using this code given below

<?xml version="1.0" encoding="utf-8"?>
<openerp>
	<data>	
<record id="product_normal_form_view11" model="ir.ui.view">
            <field name="name">product.normal.form</field>
            <field name="model">product.product</field>
                  <field name="inherit_id" ref="product.product_normal_form_view"/>
			     <field name="arch" type="xml">
			
				<xpath expr="//field[@name='description']" position="before">
                    
                    <button name="update_descrp"  string="Update Description" type="object"  icon="gtk-apply" />                 
                </xpath>
						<xpath expr="/form/sheet/notebook/page/group/group/field[@name='list_price']" position="replace">
                 
                                <field name="list_price" string="Price"/>
                                <field name="design"/>
                        
                            <label for="m_length" string ="Size(M)"/>
                                        <div>
                                        <field name="m_length" placeholder="length" style="width: 45%%"   />
                            			<field name="m_width" placeholder="width" style="width: 44%%" />
                                                                           </div>
                            <field name="dyes"/>
                            <field name="min_price"/>
                            <field name="origin"/>          		
                       		</xpath>
                       		<xpath expr="//field[@name='default_code']" position="before">           	
                            <field name="market_value"/>
                            <field name="fringes"/>
                            <field name="selvedges"/>
                            <field name="supplier"/>
                             <field name="colour"/>
                            <field name="age"/>
                            <label for="f_length" string ="Size(F)"/>
                                        <div>
                            <field name="f_length" placeholder="Length" style="width: 45%%"/>
                            <field name="f_width" placeholder="Width"  style="width: 44%%" />
                           </div>                   
                       		</xpath>			
			</field>
		</record>
	</data>
  </openerp>