cant download anything

i cant remember my administrator user name and password so i cant download anything like itunes or whatever. ive tryed to start it all up again once but it didnt work. what do i doooo

You will need to start up from your OSX install disc and follow the instructions in the relevant section of this support article:-

Mac OS X: Changing or resetting an account password

Edit
This will reset the password, but how could you forget the user account name? Sounds a little iffy to me (Apologies if this is not the case).

Actually I don't know my login either. Is there a way to find out? I know my passwd, but my Mac is set for auto login...so I never need to enter the login. I need to enter the passwd when I install programs.

Thanks.

System preferences/Accounts

In accounts I have my first name and space and then last name. Something like:

Curious Learn

Is that the login then?

Thanks.

Should be