how to display last login date?
for an example, we log in to the system on 11 april 2014. then, log out.
when we log in back the system on other day, for an example 26 april 2014,
it will display back where the last date that we were log in (11 april 2014).
thank you.

You can either

a) keep a record of all logins in your DB and display the previous one.

b) Store a last login date in the member's DB, when they login get that date and store it into the session before you update it to the new date.