Nice job spec5 and you've gotten great advice from folks here.
Pay attention to proportions and use a well tied fly or a pic of one as a model to help guide you. The proportions for different types of flies reference the dimensions of the hook both in terms of the tie in point for the material and their length. Although there might be some variation for different styles of nymphs dries etc, here's a pretty good general description that might help:
Proportion in Flies
Dubbing-- It doesn't take much-- just try to color the thread as opposed to using a noodle-- for now just use the single strand of your tying thread and twist in on counter clockwise between your thumb and index finger.
Hackle-- the Adams does have two feathers, the mix of brown and grizzly is a key ingredient of the fly. To measure the size of the hackle, without a hackle gauge, bend the stem of the feather around the shank. If the barbs are roughly 1 1/2 - 2x the hook gap, it is sized correctly. In most cases, you should be able to do this without plucking the feather from the skin until you find the right size.
The density of the hackle collar depends on how many wraps you take. In a Catskill style fly with one feather it's typically just 5 or 6 wraps-- 3 in back of the wing and 2 or 3 in front of the wing. More heavily hackled flies designed to float in fast water like Wulff patterns will have many more turns of hackle to form a dense bushy collar.
Good luck and keep at it!