Adding a foce to a certain limited region of a surface of the solid

Hello everyone,

I have a beam , and the force is acting on the top surface of the beam , but only in a certain region. Hence, I should not select the entire top surface as the surface acting for the boundary load, and neither is the force an edge load. Hence, how should I select this region (say it has a certain shape) , so as to apply force to only that part of the top surface. I really do not know whether this is a trivial question or not. I am very new to comsol , and hence not familiar with this.

Thanks in advance