I created a model ( it is not one object ) and it has many UV map textures. I want to save it properly with the file so I don't lose all my work. How do I do that ? I also want to upload it to sketch fab with the HDRI image for the environment background and with the textures, how do I do that ? please help me ASAP
Just save all the textures as image files (probably .png's) in a folder near your .blend file and save the .blend file. If you upload the .blend to Sketchfab it should bring all the textures with it. I am not sure about the HDRi though.