How can I change a file name to lowercase instead of capital?

I have a picture I have to upload to a website for a contest, and it's a GIF image, but the site says I need it to be in lowercase...which I'm not sure how to do? And when I put the file and change it myself, it still say's its wrong, and it says its %26quot;jpeg%26quot; which isn't accepted either.How can I change a file name to lowercase instead of capital?right click on the picture and left click rename and change it thereHow can I change a file name to lowercase instead of capital?right click file, select rename and end it with .gif



example: myfile.gif