Hey @Karl !
Awesome! It’s great to have several didges to help you progress!
Do you know what kind of wood it is? It’s a true cylinder!
It’s normal if you’re struggling a bit at the start, an F is easier to play than a C 
Keep it up!
As already mentioned, a mouthpiece should be 30mm. Do you have one that size?
You’ve come to the right place, I just made one this morning, my new didgeridoo is coming along nicely 
I took a photo that kind of sums up the steps
In the first one it’s already glued and I made several cuts after gluing to tune it, but the principle is there.
You cut a piece of wood, you drill it (I’d recommend using a drill press) with a 30mm bit and you glue it! (personally I place the didgeridoo upright, with a barbell inside it, that’s the right dimension
) that gives you photo 2On the inside, you need to even out the mouthpiece with your didge, I use a sanding bit
On the outside, you rough it down, you trace your circle, and you sand, you sand…
After that you can break the edges slightly so it’s not sharp!