There are many ways to backup your data. One of the most common ways is to use an external hard drive or thumb/USB drive. With an external hard drive you can drag and drop your files from your computers hard drive right into the external drive.
Another method of backing up is to use a cloud service. Examples of these services include a personal google drive account, dropbox, iCloud, or microsoft onedrive.
If you have data on an iPad you will need to sync your iPad to a personal iCloud account. Explanation of how to do this is on the iPad page of this website.