If flying in VMC = Visual Meteorological Conditions, which means you have enough visibility to safely avoid other air traffic and terrain. IIRC it's at least 5 statute miles. You must also maintain separation of clouds and any other meteorological conditions that would obstruct visibility. Any time you are flying VFR then you squawk 1200.
Flight into IMC =Instrument Meteorological Conditions, basically flying into clouds, fog, etc. requires coordination with ATC and filing an IFR flight plan. This can be done in the air. When you are under IMC and flying under IFR you are assigned a squawk code.
So depending on the weather at the time the pilot should have either avoided any weather or filed for IFR and then would be given directions from ATC. But the pilot would also use his charts to know and avoid any terrain or towers, buildings, etc.
Hope that helps. Been a while since I've flown but that's it in a nutshell.