RE: Who can post (or tell me how) a PDF/Sketch?
I take it that you want to post a PDF file.You will need to convert the PDF to a JPG file. You can do that if you have paint shop pro or other image editing software. Just open the PDF in that program and save as a JPG file format. When you do the 'save as' command, you will need to indicate the 'type' of file you want to save it as.
Good luck.