Most bb/st/pl whatever who are into their program have difficulty 'gaining muscle' and 'losing fat' at the same time. They are at an equilibrium of sorts - they can bulk or cut, but not both easily.
However, you sound like you may be new to this and are not yet at that equalibrium, so it may be easy for you to gain muscle and loose fat by cleaning up your diet, doing some cardio, and lifting.
Here's a simple rule to help with diet:
Just say No to sugar, alcohol, fried food, salad dressing, pasta, potatoes and rice.
Just say Yes to Protein shakes (1 gram of protein a day per pound you way - for starters).
Good luck and remember to take before and afters.