Why do you have mold in the lawn? Have you gotten a lot of rain?

no, a lot of shade

maybe its moss?

Where do you live?

What kind of grass do you have?

What is the nature of the shade? Is it from a surrounding forest of trees, buildings, fences, etc.?

What is your watering schedule? How often and for how long do you water?

We will eventually give you a good answer, but we just need more info.