If I backup my iPhone will all the information on my phone be deleted?
No.  A backup only copies the information to a remote location. The original information on your phone will remain. The backup preserves the information, should the information on your iPhone become damaged. It also makes it easier to transfer this information to another iPhone.

If you backup your iPhone to a computer (connected via the USB cable) using iTunes and check the box next to "Encrypt Backup", you will also backup all of your saved passwords.