Backup: . Back up the internal and external memory files to the PC Restart the TWRP. Go . backup in the Storage tab, select sdcard. Click OK and select all the check boxes. and then Swipe to back up. With this backup if something goes wrong in the installation got back to where we left off.
installation: Still in TWRP between the tab Wipe. From a Swipe to Factory Reset. Then click Format Data and keyboard type “YES”. Go Advanced Wipe, check all less sdcard. and Swipe to Wipe. Go Install. Click Storage and select sdcard . and then click OK Click the CM13 and Swipe file to Confirm Flash. After you finish click the GAPPS and Swipe to Confirm Flash. and ready Click Reboot System. Backup Restore: in TWRP click restore and click the single file appears And then Swipe to Restore.
Credits: John Michael Smith
Source: Sultanxda / XDA Emerson