Installing Custom Recovery is the first thing to do if you want to backup or install custom ROM on your rooted device. You need to go through our post How To Install Custom Recovery On Android to know how to install the custom recovery on your device.
First of all, you need to backup all your apps in your android and for this, we suggest you Titanium Backup that will work on rooted android and give you the complete backup of all your data. Save the backup file on your SD Card.
Now while installing your custom ROM on your device will make the factory reset and all your apps will get deleted and have to restore all that using the backup file of titanium backup that you had made in the first step.