I assume the problem is that you need to do as stated - update to iOS 7. Numerous apps in the app store require iOS 7 or greater to work on iOS devices. Having said that, backup your iPad FIRST. Afterwards, create duplicates of your precious data and save it in a folder on your computer. When you're finished doing that, put your iPad in recovery mode and let iTunes restore and update it. Instructions can be viewed via the following link.
https://support.apple.com/en-us/HT201263