1: Create a new class named Tile
2: Generate a list of Tiles in order to fill up the tilemap
3: Run a loop through each tile to determine if the player is colliding with the tile.
player.Left <= rectangle.Right &&
player.Right >= rectangle.Left &&
player.Top <= rectangle.Bottom &&
player.Bottom >= rectangle.Top
4: If the previous condition returns true, determine if the player's midpoint is above/below/to the left of/to the right of the tile's midpoint. (This is used to determine if the tile is being used as the ground, a wall, or the ceiling)
5: Manipulate Player's position according to step 4
There is a more optimal way of detecting collision, but I found this method the easiest to understand.