By now, you should have gotten a PM notifying you of your new password, along with a link to the new forum (If not, email me at cynicalairrick[at]gmail.com, just replace the [at] with @). Copy and paste this password into the login form at the new forum, along with your usual username. Here's where you shouldn't freak out, you will get an error message about security settings being upgraded. You will only get this message once, so ignore it and enter your new password again, this time you should have success.
It is
IMPORTANT that you change your password since, as you have noticed, the new password is incredibly difficult to memorize (we don't want any difficulties logging in right?). So go into your new account settings by clicking on your profile link in the navigation bar:

Next, you want to go into your
Account Related Settings:

From here, you can finally change your password to one of your own pleasure. Follow the image below for fields you will want to fill in in order to achieve this.

You may also optionally create a Secret Question in case you forget your password some day, but it is not required.