I need a 1” threaded headset to rehab this cheap old folding bike (I think). Do I need to know anything special besides this when searching for the part?

I’m pretty handy, and I ride daily, but my knowledge on parts terminology is lacking a lot. Just found out this is a threaded headset. I’ve heard headset before but didn’t know what that was. The bearings are shot, and stuff comes loose when steering so the fork wobbles.