It's really easy, and it's a great way for people to get an idea of what other fans think about the album.
Step 1: Enter the thread for the album review you'd like to rate.
Step 2: Click the "Rating" drop down menu on the top right of the page.
Step 3: Select the rating you'd like to give it, then press rate.
Thats all. The rating you gave it has been added and you should see the average for the album.
If you're looking at the list of reviews you'll see it's rating next the thread name.
The ratings that show up are the average of all the ratings it's been given. So your rating was added, and refelcts that through the average rating shown.
It's really simple, but if for some reason you have problem, you can send me a PM and I'll help you.
REMEMBER: You are rating the actual album based on your own opinion, not the album review.