Sup Fitness fellas, I came here to ask you how do you work on your thighs and glutes?

For the past few months I think 3 months to be exact i've been doing sit ups every night, the links are the types of sit ups i do. I really want to work on my thighs and glutes now as well. Also since i've been doing these sit ups i still don't have a six pack yet but looking in the mirror i can see that i'm almost there but what i think is keeping me from my six pack are my eating habits which haven't been great but aren't terrible either. Thanks for your help in advance.

www.youtube.com/watch?v=xumSkUpgeBA&feature=BFa&list=PLC45E89E1D7F7520C
www.youtube.com/watch?v=xumSkUpgeBA&feature=BFa&list=PLC45E89E1D7F7520C