how can you add Remember my password

Umm. Those are already in the D7 default logon box. So why do you ask?

Remember My password is there?

Yes, it's directly under the password field. In Dolphin it's "remember me."

i see Remember Me but that don't save your password so you don't have to type it again or even

It does, and if that's not working, then it may mean something isn't working right with your site's cookies.

where is that file or something

My site doesn't remember logins either, looking for a solution

Have not tested this, but you can try whats posted here.

http://www.boonex.com/unity/forums/#topic/D7-0-4-Remember-Me-issue-.htm