Thanks for the feedback! I wish I would've spent more time making the menu more intuitive since its a pretty crucial part of the game but I ran out of time.
The main goal is to make sure you have net positive food and shelter to sustain a growing population.
All improvements can be built by a single unit, but farms require units working on them each turn (+2 food per unit) and houses require 8 of the wood resource and 6 of the earth resource to build and permanently provide +6 shelter. To harvest the "earth" resource you need to use the "dig" command on a unit (+1 earth per unit on the tile). To get wood you need to use the "work" command on a "forest" tile (+1 wood per unit). Building a "tower" costs 16 wood and reveals new tiles that you can use to harvest more wood and earth, and build more farms and houses.
Population cannot grow higher than shelter, so when new settlers arrive shelter must be built to accommodate them by the next turn or they will die. And if food reaches 0 then units will die each turn until food output is positive.
Splitting units into smaller groups (i.e 6 units on one tile -> 3 units each on 2 tiles) is important for maximizing the amount of resources you can get each turn. I gave brief instructions on how to do this in the description because its a bit counter-intuitive.