Making a hole in Assembly-mode

Hi, I am new to SolidWorks. I made a fan-house, and would need to make a hole as the drawing (125mm) through the plate to get a hose in there, since I don't have access to SW right now. Can someone please help me to make that hole and describe how to do for next time? I need the dxf from the inside-view I believe, to get the right dimension while cutting the hole.

Thank you!