You can sync content to the iPad by connecting it to your computer and selecting it on the left-hand sidebar of your computer's iTunes (you can enable the sidebar via option-command-S on a Mac, control-S on a PC) and then use the tabs on the right-hand side of the iTunes screen to select which of your iTunes library to sync to it.
You will need the current version of iTunes installed on your computer : http://www.apple.com/itunes/download/
Syncing media : http://support.apple.com/kb/HT1351
Syncing photos : http://support.apple.com/kb/HT4236
Syncing apps : http://support.apple.com/kb/PH12315
Syncing with iTunes : http://support.apple.com/kb/HT1386
If you haven't synced the iPad to that computer before then you may also find this page of use : https://discussions.apple.com/docs/DOC-3141