Are you asking how you create a url that does all of that in one hit?
I don't believe you can. There may be an optional plugin to do this but I couldn't find anything.
What I am trying to do is take payments on my main site, then enroll them in that course on moodle.
What would you recommend as a process to do this?
And thank you for your response!
Firstly what software does your "main site" use? Something might well exist.
Failing that, custom code will need to be written. This can all be done using Moodle's Web Services. See Using_web_services
It a wordperss blog. PHP is no stranger to me. I swear I read somewhere that this can be done with one call. Just trying to find the format again.
Thank you for your time.