is there a wau for a beginner to calculateh the sett for dpw

You could wrap a ruler. Wrap it with all three yarns, the thick and two thins, to properly represent what is going on in the warp and the weft. Wrap it for one inch, and just let the yarns fill out their own space, don't try to force or squash them. Then count the number of threads in your wrapped inch and divide by two. That will give you a reasonable sett to begin with. Go a little bit lower if you got a hard to manage number, like if I wrapped 34 threads, which divides to 17, I would use 16 as a starting sett.

Once you have a starting sett, put on a short test warp with your yarn combination and try it out. If the fabric at that sett seems a bit stiff, cut off, resley to a more open sett, and try again. Sett sampling when you use a new to you combination of yarns is a good idea. It will tell you so much!