I offer the following options.
1) Venture into windows control panel, find "programs and features", then Roll back (uninstall) IE9, so that you've got IE 7 again.
2) Use a different email client. For my "non-computer" friends and family, I configure "windows mail" for them. Then, browser issues become a thing of the past. Added benefits: computer will let you know as soon as mail comes in; address book can be used with MS office; web links for email addresses work, etc. You may need to set up your AT&T mail account instead of Yahoo mail with windows mail though. AT&T should be able to help you through that.
3) Contact the store you purchased the desktop for support on configuring your browser. Chances are, there's a tiny little browser setting that needs to be searched for, and changed. Dealing with a live person, face to face, will be easier than over the phone.
4) double check settings for "java", and make sure it is enabled and up to date.