First, try to gently blot with a paper towel. This will help soak up the beer into the towel instead of the shirt.
Next, it's suggested that you soak the item in water with a bit of vinegar and a bit of dish washing liquid mixed in. You could also use your favorite stain remover.
Then, you can throw it in the washer as usual. Just be sure to check after washing to make sure the stain is all the way gone before you throw it in the dryer. The dryer will bake the stain in for good, if it isn't all gone. You may even want to hang the shirt to dry, to double check, instead of using the dryer.