How to use profile 2 to display user profile page with comments enabled? I have  Downloaded, Installed and enabled profile 2, profile 2 pages &amp; profile 2 group access ( i have organic groups)

Then went to permissions View any profile (all users), View own profile (authe. , admin), Edit own profile (authe. , admin.)

After which i Went to Config > People > Account settings > Manage Display > Custom Display settings and checked user account.

Whats are the next steps that i should do, or are missing, that i should have done, inorder to enable user profile page along with default comments enabled on this page ?
Not sure what you mean by default comments, but I doubt you can use core comments with Profile2 entities. The comment module only works with nodes.

See this core issue for work being done in this area.

Check the Profile2 issue queue for potential workarounds for comments.