My account was recently unsuccessfully accessed, because I received the email about unsuccessful logins attempts and with the link to "go back to Facebook via clicking link".
I am concerned who was trying to do this. How can I obtain information about IP?
There is no way to obtain this information. You can only view currently logged in (aka Active) sessions (and their IP addresses) via the Account Security tab.
If you are worried about the security of your account you should change your password and consider turning on login-approvals via the Account Security tab. This will then send an SMS to your phone with a unique code to enter during the login (when logging in from unknown devices). You can also generate the code using the Facebook for Mobile apps.
More account security info can be found here: http://www.facebook.com/help/?page=203917589649396
