Where do you fill refrigerant ?

I will assume you mean recharge the AC system. From the air compressor you will see two metal lines coming out. A thinner one and a wider one. The wider one is the low-side (lower pressure side) Follow the wider one till you find the schrader valve.

silverish looking pipe right by your windshield washer fluid bottle . its got a air valve like a wheel on ur car tip on itwith a black or blue cap.