You can only do 600 MB at a time, but you can do multiple files to back up as much as you want. Data & Apps, or just Data (and install the apps again separately)
In the app drawer (Top-right corner of the Home Screen); should read "App Backup" or something similar with an icon that looks like a folder with a arrow on it.
The information on this place is very useful. I would like to ask permission to use some of the info here on my site.I will not just copy and paste, I will put them in my own words and give reference.Thanks