How can i rotate static mesh?

i have created a sphere and i want to rotate it by blueprints. how can i do that?

In the blueprint, either SetActorRotation which sets the actors world rotation.
Or use AddWorldRotation and pass in a value in either axis.
This will need to be done in a tick if you want to constantly have it rotate.

Convert your actor to a blueprint
Open blueprint setup your Event Graph as follows:

Use the Event Tick node connect to SetActorRotation

Add a GetActorRotation, Break Rotator, Addition and Make Rotator node.
Return value from Make Rotator is connected to SetActorRotation

Nb for the addition node set a value say 30.0 and connect this to the Z (Yaw) this will give you rotation around the z axis.