I do not know how to add texture[/quote]
Do you mean how you determine the textures to apply to the OBJ file?

If so, the OBJ file should be accompanied by a MTL (material) file which specifies materials (possibly including texture names) to apply to the data contained in the OBJ file. The material file has the same name as the OBJ file, except it has an .mtl extension instead of .obj.

Also, just a warning - your obj file reader assumes a very specific implementation of the OBJ file format (e.g., only 3 vertices per face). If you're sure you'll always be using that particular implementation, that's fine. But the OBJ file format allows several different constructions for the face data.

In any case, you may be interested in this description of the OBJ and MTL file formats.