Following video covers 'Prop Overview'. It is a more in-depth tutorial on how to use different variety of props in Left 4 Dead Hammer.
Covered Props include:
Tutorial also includes how to create a rotating fan.
Prop_Static: physical model that acts as a solid object. It cannot move, animate, or accept input. Prop_Static doesn't actually exist as an entity after the map has been compiled. The vast majority of models in Valve's maps are set to prop_static.
Prop_Physics: used to add rigid, v-physics simulated models. Cannot be parented.
For multiplayer maps use prop_physics_multiplayer or prop_physics_respawnable.
Prop_Dynamic: used to add a moving or animated model to a map. Prop_Dynamics are able to be parented to the other entities, thus making them moveable and animatable.
Prop_Ragdoll: simulates physical joints inside a model. The model must have joints already in-place for prop_ragdoll to work.
Creating a Rotating Fan:
Use a prop_dynamic for the fan blades.
Insert an entity prop_dynamic and choose fan blades.
Create a brush with invisible texture applied. Place it under the fan.
Tie the brush to an entity func_rotating by selecting the brush and press Ctrl+T
Name func_rotating with fanblade. Name could be anything you want.
Select the fan blades.
Go to object properties and under parent, input the name of the func_rotating entity.
Func_Rotating flags tab, set to Start On.
Set the speed and any other properites under func_rotating that you want.