Da Gym

I just recently joined a gym and would like to get into shape. At the moment I'm 5'11" and 234lbs. I've already been to the gym a few times and so far my regimen has been thus:

30 minutes on an excercise bike (each time I go I raise the difficulty level by one).
And after that a bunch of time spent on the strength building exercising machines (mainly focusing on arm and leg strength).

My question to you is what is the best way to lose weight and/or build muscle. Keep in mind that I have ditched the junk food and have begun eating healthier.

do a lot of abs work.. focus mainly on your abs to lose a lot of the weight, then worry about turning it into muscle.. The excersize bike is a good idea too.