Dear Mehul,
For Contact Us page, you will need to write a script to receive the details submitted by visitor in an email. You can expect help from technical expert on this in sometime.
When save Item Group, system created a Page Name for it. You need to specify that Item Group in Website Setting. Once its done correctly, system will list all the list items under that group on your website.
Page name is updated when Item group is saved with "show in website" checked.
Specify the same page name in Website >> Website Setting.
After this, system will create an option called "Phone" in top bar of your website. This page will list items under Item group "Phone".
Check
http://testacc.erpnext.com for example.
Hope this helps.
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Thanks and Regards,
Umair Sayyed
www.erpnext.com