Download the LineageOS 14.1 Samsung Galaxy S6/Edge
THIS IS AN INITIAL BUILD WHICH MAY NOT BOOT AT ALL. HAVE A BACKUP BEFORE FLASHING THIS AND TRY AT YOUR OWN RISK. Installing a custom ROM on a Galaxy S6 (zerofltexx) may require the bootloader to be unlocked on the Galaxy S6 (zerofltexx) phone, which may VOID your warranty and may delete all your data. Before proceeding further you may consider backup all data on the phone. You are the only person doing changes to your phone and I cannot be held responsible for the mistakes done by you.
Download GApps LineageOS Nougat
Installing Lineage OS 14.1 for Galaxy S6
Now you can proceed for flashing with your already have custom recovery. If you don' have you can read the guide to install twrp recovery on your device first.
Do this with cautious, don't recklesly flash it to your Galaxy S6 or Galaxy S6 Edge.
Note: Video above was randomly taken from google search
Credit: Developer J0SH1X
Recomended reading : Enable Native Root on Lineage OS or replace it with SuperSu.