Here is an excellent video on how to properly clean them. It will explain everything for you :)
Here it is: https://www.youtube.com/watch?v=kbG3H-EeZ-s
In summary:
1) It's best to only clean microfiber towels together with other microfiber towels.
2) there is special microfiber towel soap that you can purchase, but it's not required, regular soap is sufficient.
3) wash in hot water, normal cycle (don't use fabric softeners)
4) when drying, heat is the enemy! use air fluff option if available