Not sure if iPad
apps are different from WIndows apps, but there should be a UserCP button up on the top menu bar. From there you should find a list of things on the left to play with. Start with 'Your Profile', and you can edit your details. If you add a profile picture, that will appear on your home page. It is different from your avatar, which is lower down the list, under 'Settings and Options'
Hope this helps - it's a little time consuming at first, but once you get used to it, it's easy as pie!!