OpenRA Resource Center

There are a lot of misplaced tiles, which are not even connected properly. You should also add at least one mine to each base of the 5 players at the bottom, as the resources are too far away at the start, and the top player can rush them very fast. Also try to add some more terrain variety, as the map is basically one big open space.
As to the player slots where the last slot must be spawn F, you can lock the spawns to player slots in the map.yaml file:
Close to the top you should find player references, it should look like this:

PlayerReference@Multi0:
Name: Multi0
Playable: True
Faction: Random
Enemies: Creeps

If you add this:
LockSpawn: True
Spawn: 1 #Numbers correspond to slots
LockTeam: True
Team: 1

you can lock the spawns and teams according to slots - Multi0 is slot 1, Multi1 is slot 2 and so on. Note that it must be on the same level as the Enemies or Faction traits are.

The spaces (offsets by the code) were automatically deleted by the website, but you should look at the yaml file where you will find the correct spacing.

Thank you for taking the time to look at my map!!! And for offering your advice. I agree, it needs a lot of work. I just threw it together so my buddies and I would have a fresh challenge on game night. I'm about to revisit the editing.
Thanks!

I'm glad I could help : ) There are a couple useful sites that concern lua scripting and yaml editing that really helped me when I was starting:
Yaml traits: https://docs.openra.net/en/latest/release/traits/ - It's basically a place where all the things that could describe an object in the game world are. There are usually references as to what each trait should be attached to.
Lua scripting commands: https://docs.openra.net/en/latest/release/lua/ - It doesn't explain the basics of lua scripting bu it covers the commands that are used by the game and which you could use in a map.
Github Wiki: https://github.com/OpenRA/OpenRA/wiki/ - there is a quite nice guide on map creating (mainly about editing yaml files) and scripting.
Basic map options: https://github.com/OpenRA/OpenRA/wiki/Map-Options - Here you can find how to edit options in a map
World coordinates system: https://github.com/OpenRA/OpenRA/wiki/World-Coordinate-System - This will help you to understand 2D and 1D world coordinates.
Those are the main ones, but on the Github Wiki you can find many more guides.