If your goal with "arm flab" is just to get rid of the fat, then just lose weight. Your body will use up fat equally throughout your body as it burns the calories away. There is no way to specifically target fat on any part of the body. You can target a zone by toning the specific muscles, but if there's a layer of fat in the way, you won't be able to see the muscle tone as well until that fat's gone.
I started seriously working out (cardio only) about a month ago; added strength training about 2 weeks ago.
What I do is this:
Day 1: 20-30 minutes cardio, then 15-30 minutes strength training
Day 2: Cardio only
Day 3: Cardio only
Repeat
I put 2 days of "rest" between each major strength training day. The cardio activity varies; on some days I walk, others I swim, still others I do aerobics. I've lost a total of 6 lbs so far. Kapeh12 listed several good exercises to do; push ups are especially recommended, since they work your arms, shoulders, and abs. If you lack space on the floor for knee or regular push ups, or have difficulty with them, try wall push ups to strengthen your muscles.
For extreme fat burn, water jogging is excellent if you have access to a pool. Done properly, you can burn 11-13 calories every minute! The deeper the water, the better.