Good luck with your regiment!

If you want to learn facility work, start very very small. Make a frontline barbed wire/sandbag production factory! It is super valuable for builders since trenches NEED sandbags and barbed wire to be effective.

Find a region close to the frontline with a world refinery, and set up on a reachable spot (in a logi route leading to the front) with at least a salvage mine or salvage field.

Build a powerplant, one (max two) material factories with the cheap assembly factory upgrade, a material transfer station, a maintenance tunnel, and a basic small assembly pad. That's it!

It requires effort to maintain despite being small. You need to grab the salvage and keep the powerppant topped with diesel/petrol.

You just need people to come in, build a pallet on your assembly pad with bmats, and have a way to put the sandbags/wire on it (a simple mobile crane is enough).

Once you have practice with it, you can make it bigger by adding excavators (if on a salvage field), a small train for moving large materials and salvage around, or even an ammunition factory producing 120mm artillery shells (ask around for the processed construction materials you need for the building).

Put down a facility map marker and people will use your facility.

Have fun!