Do I file W-2, or 1040, or both?

So I Have a Main employment Source of income (Hence and W-2 Filing form and a W-4 Withholding form), However I made some side money selling art commissions (the net gross of that was just under $600) and apparently from talking to people more experiences with tax filing on here, that meaning I should qualify for the 1040 Section C Form (since the min threshiold of that was apparetnly $400). So, when tax season comes around. Which form do I end up filing, The W-2, or the 1040 Section C Form? Or do I file both.

 

Detailed answered are much appreciated.