We have all done this in the past ... Rip the stuff off. Smooth the wall by removing glue with a stiff putty knife. Patch the holes with drywall compound unless you are a purist and want to use spackling. In some cases, it is even easier to skim coat the entire wall ... but you are just getting started, right?
Get a sanding pad and pole with a screen. This outlasts sandpaper and makes the job go faster. Once the surface is smooth, you can prime the walls and paint. DO NOT use the so-called "W" pattern while painting. Cut in the edges and corners, then paint smoothly up and down the walls with a good wet edge overlap.
YOU CAN DO IT!