hi,
my portal is correctly running with other username and password and how i can change it to my username and password. can anyone please help me.

If you meant that your "Team Site" (or other type) is running with other user like "Administrator" for example, you can change the user in the top of the page. Just click in the "Welcome " user name, a menu will drop down, then click in "Sign in as a different user" and use your account.
If this is not what you meant, please send more details (site collection, owner, etc).

Regards.