Man oh man... another guy new to the gym who wants to focus on just abs and biceps. I'm surprised you didn't include chest.
DO NOT GO FOR SINGLE BODY PARTS.
In a single week, you have the time to work out EVERY one of your body parts and grow dramatically throughout your full body. Do not just focus on that 6-pack and biceps. You'll grow all weird, have lower back pains because of straining abs but no lower back workouts, you'll be disproportioned. What you need to do is create a TOTAL body workout, which is doable over the course of a week.
You won't get big and bulky overnight. It takes years to do what professional body builders do. You can stop and go as you please, but while you're in the gym, at least TRY to work yourself to grow at your maximum potential. It's a waste of time otherwise.
If you aren't fat, then quit worrying so much. BULK UP. Put on some muscle mass. The more lean clean mass you pack on, the less your total body fat percentage will be. If you don't have much muscle to begin with, adding some mass might be just the thing to pump that 6-pack.
Actually, now that I think of it... 160 is pretty heavy for a 5'7" who just joined a gym and is unsure of what to do. Have you done any sports. I'm not sure if what you have is body fat or muscle mass, so you'll need to figure out what you feel like you need and do it.
BUT NEVER WASTE YOUR TIME IN THE GYM. Focus on full body split workout routines. Squats, deadlifts, bench, curls, pullups, lats, french presses, the whole deal. Work each muscle group once a week, and improve every week. Split it into a 3-4 day routine. I aim for 3 sets of 4-6, I remember someone reccomending 5x5 on this site, but the goal is to overload your muscles to growth, so pack some heavy weights.
Think about what you want to do first. Do you want to cut, or do you want to bulk? When I say bulk, I don't mean look like Arnold. I mean, put on some muscle by having a surplus diet and working hard.
I just jonied west coast fitness... 
