Ok I will help you. First you have to press upload and go to the section "Images and videos" After that press the button upload and it should show you could choose a file. So click on that and your files will come on your screen. So go to the top and type in %appdata% then find the file .minecraft Then after that you will see a file called "Screenshots" Double click on that then double click on the screenshot you want to make the planetminecraft upload look like. Then once you double click the screenshot you want your files will go away. So then it should show on planetminecraft your file you chosen. Then just press save let it save and then your done and go ahead and do the rest of the upload :)