I don't think your sentence is correct. You can't use これ followed by a noun, if you want to do this, you need to use この. Your sentence should be これはリーさんのりんごです。(kore wa Lee san no ringo desu) - This is Lee's apple. or このりんごはリーさんの。(kono ringo wa Lee san no) - This apple belongs to Lee. これ must be followed by the particle は (or が in some cases) and この by a noun. The same thing happens with それ, あれ, その, あの, etc.. ONE of the functions of the particle の is to show possession. これはリーさんのりんごです。(kore wa Lee san NO ringo desu) The noun after NO is what belongs to what came before, in this case, Lee, so he's the owner of the apple. You said: りんごのリーさんです。(ringo no Lee san desu) So basically you said that Lee belongs to the apple xP