Basically
the gitrog monster draws you cards EVERY TIME a land goes to your graveyard. Also you must sac a land or he goes to the graveyard. So basically during upkeep sac your
drownyard temple, draw a card, then draw a card during your draw phase (+2 cards in hand). or you can use
Dakmor Salvage so that you can sac it, draw a card, draw phase, draw another card, dredge using
Dakmor Salvage's effect, mill maybe 1 or 2 extra lands (then draw +1 or +2 extra cards). That's basically how it works.