Read up topology and what clean mesh is.
Keep on modeling, I'd avoid sculpting until you can model.
I consider(I think this definition is truly what it means)
modeling where you extrude and move verts , faces and such around.
Sculpting is where you sculpt a ton of verts ,and usually your mesh will turn into a mess. Unless you use a base mesh or the program your using is good(Blender is good but somewhat difficult to sculpt from say a subdivided primitive) , or possibly your proficient in sculpting.