In your photo editor, find the file re-size tool and set the file size to 640x480 or 800x600 pixels.
Don't do this to these files or they will be extremely pixelated (jaggies). Work from the original picture files.
If you didn't keep the original picture files, get out and take a new set of pictures.
Looks like a great entry to the build off. Pictures make the difference.
I built one like that with BMK handle bars in the '80s. Wish I knew then that they were cool, I hated that bike all my friends had BMXs. Now I know better and wish I still had that bike. I'm going back to building bikes like that.