After a few little Mishaps when setting up my first forge, I finally got a fire going. Here's my setup.

And a short video of the heat.

I made a few beginners pieces. A round and a square drift and two nail like contraptions with a bend hook for a head.

 

Looks like a good start!  You may want to build up the sides of the firepot with fire bricks to make more of a trench for your charcoal and probably prop oven the ash door as I'd guess that blower would put out WAY MORE AIR than charcoal needs.  Doing this will save on charcoal and on steel as too much air is prone to burning pieces up.

Thanks for the tips Thomas. I indeed have the feeling that my fire isn't deep enough.

Would it be better with coal? I want to practice first a bit with charcoal, becuase real coal is not easy to get.

 

Your forge looks like it was designed for using coal and so would not need as much tweaking to use it.  Nothing wrong with going bimodal.  I have a stack of grungy old firebricks I use to reshape my firepot depending on what I am doing and what fuel I am using.  My parents spent 4 years in Naarden and I got to visit; I have very pleasant memories of the Netherlands.

For the time being I am just playing around, Experimenting. But tips like this are very helpfull. I can luckilly regulate the blower with an old rheostat.