A drummer and guitarist I play with wanted to learn the basic blues, so I made this simple song for them to jam along to. It also gave me some practice in flat.io (which I recommend). If you copy the song (by opening the link) you can adjust the tempo up or down for your skill level. I also personally play this a variety of ways, sometimes more swingy, sometimes less notes (like if a guitarist is soloing), etc. but this is the basics of it. Anyway, thought some people might enjoy this so here you go!
https://flat.io/score/5e052a5183c1076173a4898c-walking-12-bar-blues