How to save a backup so I can restore my iphone and then get back the backup later?

I want to try to install iOS 7 but i'm not sure that it will all save if I want to go back to iOS 6.1.3. If I restore my iphone can I install an old backup back to my iphone?

Plug your phone into your computer and you have choice to manually back up your phone on iTunes or use iCloud to back up your phone. I would recommend (from experience) backing up your phone on your computer, manually. This way, all your contacts, photos, music, apps, etc are saved on your iTunes. You can always restore your phone by connecting it to your iTunes. There should be "restore" options.

I'm not sure you can go back to the old iOS if you update it… But definitely, and always back up your phone so you don't lose anything!

Yes, if you make a backup you'll be able to "restore from backup" to get your settings and apps back. However, it's not safe to install iOS 7 unless you register your device's UDID with a developer account through a site like http://www.udid.in/.It's $5, and then you don't need to worry about Apple disabling your device for running unreleased software.