You've downloaded iTunes to your computer and installed it : http://www.apple.com/itunes/download/ ?
If you haven't synced your phone to that computer then you may find this page useful : https://discussions.apple.com/docs/DOC-3141
To backup your phone you can use the File > Devices > Back Up menu option - if you are using a PC and the drop-down menus aren't showing then control-B should get them to do so.
If you have any store downloads on your phone that were done via husband's account then they will remain tied to his account - so his account will need to be authorised on your computer's iTunes via the Store > Authorise This Computer menu option, and only his account will be able to download any updates to his apps.