A google ID lets you log onto many other things other than google.
This is my first instructable so it might be a bit rubbish!
Step 1: Head to the signup page
(I know it is google mail but is still signing you up for a google ID plus you also get a free @googlemail.com email address)
go to https://www.google.com/accounts/NewAccount to use your existing email for a google ID.
Step 2: Fill In The Form
Once your done Click I accept.create my account.