Any mana you gain in your upkeep disappears before your main phase
The shop you play at will have a "land station" with basic lands for you, so don't sweat that part.) That leaves room for 23 spells of varying types
Control the board with Aetherize or Infernal Grasp, and finish off your opponents by swinging with a massive army of evasive 9/9 Wraiths
4 Snow White: Well Wisher 206/204, Amber The standard issue Legendary of Snow White: Well Wisher depicts Disney's first princess smiling as birds alight upon her, but the Enchanted shows her outright breaking into song with a few animals gathered in the background
You also need to make sure you hit your land drops, either with draw effects (Qiqirn Merchant and Adventurers Airship provide usable bodies as well as draw smoothing) or cards that directly give you lands or mana (World Map, landcyclers, Blitzball)
Since lands are the cornerstone of every Magic deck, its important to understand their functions and what makes different kinds of lands unique