I have decided to concentrate on my abs next. I am looking for info what has worked for you? Suggestions about workouts and videos.

I have lost about 20 pounds by walking and my legs are looking quite nice; now it is time to move up on my body and "tune" up my mid section.

There are dozens of ways to do abs. 1st let me advise that you make sure to balance the body with core work for the back to avoid a misbalance that makes you slouch and have back pain.

The core works every moment over every time of day or night. It takes a lot to fatigue the muscle and you won't see your hard work until you cut the fat that lies on top of it. Most models in magazines have cut to a dangerous and not sustainable body fat % just for the photo shoot, so adjust your expectations.

Now, back to the OP:
crunches: regular, reverse, bicycle. Build up to 100 of each and do all three (total 300)
Pulley pull down: kneeling toward pulley, pull down weight - forehead to floor and back up. If your back feels good, this is a fairly safe way to pull down a lot of weight to fatigue the muscle.

Weighted stability ball sit ups. Clutch a weight to your chest and go till you puke.

Butt drops. Position yourself like a straight arm plank. Bring your left leg under the body and reach up with your right arm and touch your toe. other side.

medicine ball russian twist - seated with legs elevated. touch ball side to side for 1 minute sets. Can also be done standing with back to a wall. touch ball to the wall. Much easier.

water bottle leg lifts. lay down on the ground and put a water bottel by your feet. without touching feet to the floor, lift feet (straight leg) up and over water bottle back and forth for 1 minute sets.

Romanian chair ( I call it the jet pack) leg lifts. This is important to do correctly. I often see people do this and they're working their hip flexors more than their abs. Lift legs, bent, to chest. As you do, curl your hips up and away from the back of the chair and up towards your chest. Don't let your legs all the way down. That allows for too much momentum and not enough ab effort. Go about 80% of the way down and repeat. Start with sets of ten and do 3 sets.

I've got more, but I think that's a good start.

Do all of the above in between sets of other body part weight lifting or in between 1-2 minute sets of fast cardio. (treadmill)

Wow

I did 3 planks with leg lifts 1 minute each
5 sets of bicycle (20 )
and sideways bend with 8 pound weight (x5)

Now I am spent!! -- But gotta start somewhere.

ETA I hate core work, so this is a huge accomplishment for me; to commit doing the torture. I carry my weight in my mid section, which sucks.

Keep in mind, you cannot spot reduce. Doing ab exercises doesn't burn stomach fat preferentially. This is a huge mis-conception that seems hard to squash. Everyone has 'abs' even those that do very little exercise...you just can't seem them because of the fat on top. In order to have VISIBLE abs you have to get your body fat % down. I totally think a strong core is important since it helps to strengthen your back and is needed for many exercises...but if you're doing it because "I carry my weight in my mid section" then you are taking the wrong approach.

All excercise has the potential to burn fat but your body (genetics) determines from where. The good news is, stomach fat is usually easier to burn off than lower body fat that is subcutaneous. But again, doing ab exercises doesn't whittle your middle like the late-night infomercials would have you believe.

I know Did you see I dropped 20 pounds by walking?

You gotta start small but work your way up! it wont take long for those abs thats what my brother told me anyway :P

I felt so small, after Monday. Friday's ab program was already easier. Whereas on Monday I was drying doing my 3rd set of bicycle, on Friday I was able to finish the 3rd