Pleaseee help me! I know this is asked a lot, but any advice is helpful?

I'm having a issue! *No negative energy intended* my is OKAY for my age and for being only half sicilian, I mean, boys still like it, but I don't like it too much and I have a feeling I need a wayyy better behind! So how do I do this? And I'm not talking muscle. I'm talking roundness, and fatness. I mean I have a great body but how do I enhance my behind?!