The signature you do the same way you did the one you have now. copy the link go to your signature page and paste it into the insert image button popup, then once it is there how you like save the changes. The avatar you hold your finger on it until you get a popup that gives you an option to save "image as" and then save it to your ipad somewhere you can find it. (save it as a .jpg if it asks) Then go to your account details page here on the forum under your name at the top of the page, and click on change avatar, then browse your computer for it, click it and save.