Creating texture map for .OBJ

in New Users
Hi all,
I have an .OBJ file of a gun. But it has no shader. I want to paint the colors onto it and make my own diffuse map. How can I figure out where on my image to draw for it to apply to certain parts of the gun?
I have Photoshop CC and can open .OBJ files in there if that helps.
Thanks
Comments
You can see the the obj's map in DAZ Studio by going to the camera dropdown menu and choosing 'UV View' Select View by material and click on the various materials in the surface pane to see the maps.
However, that's only a view of the mapping. To export the templates, you need something like UV Mapper. You can get the free vesion here.
http://uvmapper.com/
mac
If you go over to the Art Studio thread DestinysGarden has a great thread going giving lots of step by step on texturing
http://www.daz3d.com/forums/discussion/74272/texturing-with-destinysgarden#latest