(This guide was made in the beta version and may or may not be outdated)

first you gotta get started by doing some of this stuff

1. placing a keep
2. getting a basic food source
3. get a treasure room
4. build a grand library

Next you need to start researching

Click on the grand library and click research then click research on Dragon Husbandry

Dragon Husbandry at bottom of the research tab

After the research is done you will get the following buildings

g- gold

12 workers | 60g a year | 200hp | Dragon Roost (Required for all the following buildings)
requires noria | 4 workers | 21g a year | 10hp | Dragon Bath
4 workers | 10hp | Dragon Flight Training
4 workers | 30g a year | 10hp | Dragon Doctor

to tame a dragon you will need to build a dragon roost somewhere near fish and meat

2nd you will need to place a gold pile in the dragon roost by selecting it (1000g cost per pile)

then wait for the next invasion and a dragon will settle there

the dragon will have its own health, happines, and bond meters
if its happines and health is high enough it will begin to gain bond

Once the bond meter reaches 100% then you will be able to control the dragon like any other unit
it will also get a new outfit

Also this is my first ever guide so rate how i did.