Is there a certain brand I should look to buy?
I use the non-expensive effective stuff with not a whole lot of added junk in it.
I buy mine from Smiths, but they have the brand at Target and a lot of those types of stores.
For a tub, it's like $15-20.
Body Fortress Super Whey Protein is what it's called.
I gained 65 lbs in a year using it.
But if money isn't an issue, about anything from your local GNC/Vitaworld will be fine.
Some of the other guys here will be able to help you out more with the more expensive stuff.
EDIT- also since your 135 lbs, eat anything and everything. But when I say that, don't load up on the junk food. Try to eat healthy as much as possible. But don't kick your self if you eat junk food. Your still young.
If your skinny and not obese, I don't see a problem with eating junk food. Just be sure to eat healthy as well.