How can I work on my abs with a herniated disc in my lower back?
That's a serious situation that should not be taken lightly. A good chiropractor will be an expert on limitations of certain movements. I would see him or her and get evaluated first. I myself have Spondylolysis and have learned what I can and should not do from chiropractors. Also, a good physical therapist will be another great source to suggest proper movements and possible limitations for your situation.
I would not rely on any info received because just because it worked for someone else does not mean it will work for your herniated disc. Consult with a physical therapist so they can evaluate YOUR situation and design a routine for YOU so the situation does not get worse by doing the wrong exercises. Most states offer direct access so you don't need an MD referral in most cases