Help Me (how Do I "upload" Here)

I go to "UPLOAD" than i find my file that i want in a .zip (inside are OBJ files and a readme file with a picture of that model rendered in blender). I set it to mm. I press "UPLOAD". And.....this.

Try without the readme and blender picture - you should get a preview of what the site software makes of your OBJ that you can compare to your blender work, but nobody will look at any readme.

Thanks for the help but it still shows the same screen.

Is there anything else besides the OBJ ? If not, check if your model is within the other limits - maximum 64mb (zip file size) and 1 million triangles. Perhaps try uploading as STL instead or try checking the integrity of your model with the free meshmixer or netfabb studio basic programs. (There is also a "3d printing toolbox" available within recent versions of blender that may help determine problem areas - for 3d printing as opposed to just rendering, your model will need non-zero wall thickness everywhere just to mention one possible issue)