The Google email tutorial can be found here
To Change your Password go to 'Settings' while in 'Mail'
choose "Accounts" and "Change Password"
If you use Google Mail you will start receiving email to that account. If you have another email address that you like to use and do not want to have to check another email address you can easily forward your Google Mail to another address. Here is how:
Go to 'Setting' from your Mail account.
Then find 'Forwarding and POP/IMAP' tab and add in the email address you would like to have your email forwarded to.
That is it. Any email you get to your Google account will automatically go to the email you entered in the box.