The blueprints in RTS building template are designed to be easy to edit and build from. Each building does certain actions when buttons from the HUD are pressed, in the buildings event graphs you can find the code that runs when these buttons are pressed.

Below is the Barraks building blueprint it is setup to recruit units when button 1 is pressed, upgrade units when button 2 is pressed.

Highlighted in yellow is the upgrade unit event here you can set the unit type to upgrade, the new max carrying amount, and the max number of times the unit can be upgraded.

Highlighted in red is the recruitment event here you change the class to your own unit class to recruit it, (your own unit class must be a child of the master unit blueprint).

Below is the farm building which is setup to generate resources, this can be turned on and off using the 1 and 3 buttons in the HUD, the building is upgraded when button 2 is pressed.

Highlighted in green is the generate resource event. Highlighted in blue is the code that sets the IsGenerating value to false which stop the the building generating more resources. Highlighted in red is the upgrade function, on this node you can set some of the upgrade effects on the building.

Below is the foundary building which is setup to convert resources, this can be turned on and off using the buttons on the HUD, it also has a button to upgrade the building.

Highlighted in green is the convert resource event. Highlighted in blue is the code that sets the IsConverting value to false which stop the conversion. Highlighted in red is the upgrade function, on this node you can set some of the upgrade effects on the building.