If you're looking to add some bittering during dry hopping, you'll need to boil the hops in some water and pour the entire thing into secondary (after it cools, of course). IMHO, however, you should just toss some hops in a muslin or cheesecloth bag (if you don't have a nylon "hop bag") into the carboy and let it go through secondary.
As far as what hops to use... For the most part, dry hopping imparts aroma and not much else. Go to your LHBS and smell every type of hop they have until you find one that you REALLY like. I personally LOVE cascade for aroma, but you may have a different preference, and that's not even the only type of hops that I love for aroma. You have to make a choice on your own. Trust your nose and have fun.
Up Next: Belgian Dubbel, English Pale Ale
Fermenter 1: Blonde Ale Experiment 1 | Fermenter 2: Blonde Ale Experiment 2 | Fermenter 3: Northern English Brown | Fermenter 4: Nothing
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