Be warned! This is addicting! I got into stacking a couple of years ago and have learned a lot. Mostly by trial and error.
Here’s a thread about Zerene and some links to resources for learning it. I think Allan also does a Zerene v. Helicon bake off as well.
Zerene’s interface is decidedly antique, but the software is the bomb. Can’t speak to Helicon, but others probably can. If you’re going to combine say more than 5 images, it’s a good idea to get a dedicated stacker. It is extra money, but believe me, it’s worth it if you want good results with an easier time to achieve them.
We also have a stacking thread going that might help you with your new obsession, ahem, I mean, technique. Yeah. that’s it.