I'm just a lacky writer trying to update a wordpress site for a school that I volunteer for. I can open a page but when I try to save changes the whole thing freezes. Is there some kind of conflict somewhere? How to begin to unravel??

First thing is to gather some information
1) What version of Wordpress?
2) What version of Atahualpa?
3) Does your user have the role of 'admin'?
4) Did the problem just start happening? If so, what changed?
5) What happens if you disable all active plugins? (make a list so you know which to turn back on)
6) What happens if you switch to the twenty-sixteen theme?
7) Who hosts the site?

Hosted by Bluehost
WP version is 4.9.1
Not using Atahualapa: they're using Avada. It wasn't registered but I was just able to do that.
(Sorry if this is an Atahualapa forum only. I am so green at all this.) There aren't many plugins but it says there's a new version of LayerSlider and Mojo marketplace available. I hesitate before I do updates because once in the past the whole site went to shit after an update (but that must have been a theme update?)
Will test plugins later today but wanted to reply in case anything screamed out at you

Yes, problem just started happening and it must have been some autoupdate or something because the site barely gets touched these days

Yeah this is a forum for the Atahualpa and Montezuma themes but I'll give you some advice

Backup the database and all the files beore you do anything else. Seriously, do a backup. That way no matter what you do, you will be able to get back to what it looks like today.

Once you have done the backup, then disable all plugins and try. If you still can't add a post, swap the theme to twenty-sixteen and try again.

Actually if you really don't knw anything about how to do a backup or how wordpress works, you - and the school need to find someone who does and probably pay them to figure out what is going wrong. The more things you try, the more you might make the situation worse.

So...have you done the backups yet?