You can set iClouds up to automatically download songs, apps or books that you purchase on iTunes to your iPhone and your other iOS devices all at the same time to save you the time and trouble of doing it yourself. This feature is also helpful if you make purchases when you are away from your computer so you can access them right away without having to wait to connect to iTunes on your computer.
In order to enable automatic downloads for iCloud for your iPhone, go to Settings and then go to the iTunes & App Stores menu. This is where you will find all the download options. You can just slide on which ones you want to enable. If you have an iPod or iPad that has the same accounts, then check to make sure that they are also set up to be able to automatically download content to.
After you have enabled iCloud for automatic downloads, you will also want to enable automatic downloads for iTunes as well so purchased content will download to your library. In order to do this, go to iTunes Preferences on your computer and choose which types of content you want to have automatically downloaded.