SMAPI does the work for you once you install it from here.
RELATED: Stardew Valley: 10 Changes in the New Update We're the Most Excited For Installing SMAPI and Content Patcher are those first two steps. There are only two small steps you need to make before directly downloading mods to ensure the mods work correctly with the game files and are supported. If you're one of the many people who get too confused and frustrated at trying to manually install mods for video games, specifically your favorite farming game known as Stardew Valley, look no further.
But most games don't directly support and have a way to manage mods, making it complex to actually do by yourself. Community-made content for the community.