I want to 15 to 20 pounds but...?

okay so I'm 145 pounds and 5'8 I know its a fairly good weight for someone my height. But I have a stomach and my thighs pop out on the sides and the inner parts are very jiggly. I was a twig growing up till 8th grade then I packed on the pounds I used to be 164 170 2 years ago then I started eating less. But I'm not sure if i can loose 10 15 pounds now since I am considered skinny to most people im not sure how hard i would have to work to loose the weight or what kind of cardio i would need to do. So please help me I want to have a nice body to enjoy while im still in my 20's