Women's abs?

ovi212

I feel like my abs are still pretty soft and I'd like a really nice stomach for summer. It is actually the part I am most self-concious of. I know that you can't target weight loss, but I really don't have much to lose (I'm about 120 lbs) so can I start to firm it up? I was wondering if anyone had any good exercises for women looking to get a 6-pack or just hard defined abs? Preferably something that can be done at home. Also, how long will it take?