Plug your iPhone, iPad, etc. into your computer with its usb cable. start up itunes. In the left window your device should appear. Give it a name it it doesn't already have one. Click on it to make it active. Click on the various tabs to customize what you want to sync. The bar on the bottom of the screen will show you how much space your media takes up and let you know if your over capacity. Click on the "sync" button to the right of it. Syncing should begin. don't disconnect your device until the status bar on the top if the screen tell you you can.