1999 Cadillac Deville heats up real quick

Hi, i brought this car a week back, since yesterday i have the panel show me a high coolant temperature 270 degrees. steam started coming out of my engine after i pulled out of the road. I can barely go 2-3 miles now without the same message coming up.

please suggest me on my next step, anything i can do to fix it before i turn up my car to a service center

Thanks