In Episode 1…

It should be in your Tubmail. If you deleted the Tubmail or are too lazy to check it, the password is splodeydope.

(Move your mouse over the blacked-out text above to reveal the password.)

In Episode 2…

You must complete more missions before you are given the password. Therefore, even if you were to enter the secret password — asdf — you would still be unable to enter if you’re not yet ready.