check the manual - it's in the PDF file in the mod folder. Every class has a "starter" unit - with different requirements - sometimes a prerequisite technology, other times a required building.

Once the prerequisites are met, you obtain the unit just like any other. There are a couple of exceptions to that, however, as I believe some of the Cleric-class units can only be obtained by purchase and only purchased wit Faith, not Gold.

Oh,thanks you!Great Mod,btw.