How do I upload a capx?

I have a problem with my game that is to complicated to explain, but simple enough (i hope) with a capx. So how do I do it?

1/ Try to explain it anyways, it's always nice and better received than "here is my capx, please fix it"

2/ Use a file sharing program, like dropbox. It's free. It creates a folder on your computer, where everything you put in is synchronized on their servers, and you can do a right click on a file and use the option "copy dropbox link". This will copy the public url you will want to share here

Thanks that was very helpful.