i found this answer but i didn't know how to select cylinder faces (
So, summarizing:
1) Draw the cylinder;
2) Subtract the cylinder from the dielectric substrate;
3) Select the cylindrical face in the subtracted region;
4) Apply PEC boundary or Finite Conductivity boundary (so as you can define material ,thickness, roughness, etc.);
when subtracting the via cylinder make sure that the "clone tool objects before operation" check-box is checked.
Then you can assign a conductor or a PEC material to the via.
To select an object press O and when you click an object the whole object is selected.
If you wish to assign PEC baundary to the via faces, press F , the click on each face of via and select it. to select all faces together hold the Ctrl key.