How to get a six pack?….

What Brian said. Spot reduction doesn't work, and many of us - perhaps especially men (which I am not) - find that the abdominal fat is the last to deplete.

Of course exercises can improve your ab muscles, but until the fat above them depletes enough to make them visible, there's not going to be a 6-pack. On top of that, some people's genetically-gifted body configuration means that they may never get a 6-pack literally (could be a 4-pack or some other level of definition, once they get lean enough). Some of the fitness influencer types who have a 6-pack only have it when they're carb-depleted, a little dehydrated, pumped from a recent workout, slathered with fake tan and oil, carefully posed, professionally lit, professionally photographed, and maybe even photoshopped. It's not necessarily a 24x7 just walking around thing, even for quite lean, very fit, very muscular people.

If your routine doesn't include a good whole-body strength routine with compound movements, maybe add that. Specifically core-targeted exercises are a good thing, but whole body movement will tie things together as well as giving abdominals some useful stress.

You may find some useful advice in this thread:

http://community.myfitnesspal.com/en/discussion/1161603/so-you-want-a-nice-stomach/p1

No, I don't have a 6-pack. I'm a freakin' li'l ol' lady. I like being strong and healthy, but couldn't care less about a 6 pack. I'm just glad I don't have the shape of a couple of droopy 2-liter bottles plastered horizontally on my belly anymore, and am satisfied with just getting somewhere close to an almost nearly approximately flat belly, TBH. YMMV.