Overheating problem

I drive the Beamer all day today and then I went to put some gas in, quarter mile away after the car is at max on temp bar. I don't know how to tackle this or even where to start. My friend said I should bleed system cause some air might have gotten in after replacing coolant sensor. My other friends says I should flush coolant and replace. The only thing I noticed that was weird was that AC wasn't blowing cold and it was at 70. Was more like room temp but idk if that is any sign of the problem I have

Any help is appreciated. Thank you

Overheating problem