I love the vertical smokers too. You can put a lot of meat in them with only a small footprint in your patio. The round ones look cool, and they're usually sized to use the low-cost lower charcoal grates from a Weber kettle. Downside is the round racks/grates don't pull out like a drawer like they do in the rectangular vertical units so it's a little harder to rotate your meat or spritz or apply sauces. Still, if the price is right, what's not to like? And yours looks like any rust damage is minimal. Great find!
Pics of inside will let us know what you have and what you might want to think about making/adding. A charcoal basket in bottom is nice. Looks like you have a charcoal "chimney" which makes it easy to light and get going. You can put wood chunks on top for flavor. Or space a cast iron pan above the coals for smoking chips or pellets. I suggest making sure the exhaust vent (at the top someplace) is always set to be 2-3X the area of the intake at the bottom. Control your internal temperature by throttling the lower intake. If that feature is missing or rusted away, we can give you ideas for replacements. You'll find lots of suggestions here on digital thermometer choices, but for starters just a cheapie screw-in model with an analog gauge will get you going. 200-250F is a good temp to shoot for.
There are electronically-controlled fans for such units so that controlling the air flow (and hence the temp) is automatic, but there's a lot to be said for the old-fashioned hands-on approach and making a relaxing afternoon out of it.
I suggest starting out with chicken thighs or drumsticks. (Although you'll want to run more like 275F then.) Chicken is cheap and cooks quick so it's a good way to learn techniques. Hope you find it fun.