All right, I've downloaded the mod and loving it so far. Can anyone give me any tips regarding how to play as the D'Tesh?

my advice... play as another civ until after the next patch. The D'tesh are great, but learning them now might be a waste of time. There may or may not be some significant changes heading their way.

Well, if you want some really basic tips in the meantime, in no particular order...

1) Don't clear any nearby lairs or dungeons early on, they can procide you with slaves when the cyclops or minotaurs kill themselves attacking your city.

2) Tech to Knowledge of the Ether quickly, the binding stones remove unhappiness in the cities.

3) Death Mana, lots and lots of death mana.

4) Go to war as soon as you can unless your closest neighbor is the Lurchip or somebody else with a lot of non-living units.

this may be the wrong thread for this question, but its the closest i found.
How do you get infused ash? From what i found out, it has something to do with a pyre, witch i can't build.

you can only build a pyre (current version has workshop art) on living resources. Things like cow, sheep, pigs, horses, corn, rice, wheat, dye, etc. If you download my D'tesh Water module you will also be able to build another improvement on water tiles containing living things like kelp, fish, clam, shrimp, and crab which is called the Cremation Boats. They work like pyres, but on water. To build them you need to have the D'tesh Arcane Barge UU (also in the module).

Thx i downloaded your module, but where do i install it?

Like every module. Just place the unzipped folder into Rise from Erebus/Assets/Modules/Normal Modules