What theme are you using? Where are you trying to create columns? If you’re editing your site through the editor in appearance you’re taking a huge risk of making your site go down.
If this is a production site I suggest migrating the site to a localhost and then working on the theme files directly.
My suggestions:
1) Google: MAMP WordPress Setup (follow tutorials)
2) Use All In One Migration plugin to migrate site to local setup
3) Build a child theme. (Any changes you make to a theme will be overridden when that theme receives updates for security or general enhancements. If you want to make sure your changes stay intact you need a child theme. A quick Google search for how to create a WordPress child theme should do the trick.
This might seem like a bunch of steps before diagnosing the actual issue but you want to make sure you’re set up the right way so you’re not kicking yourself later.
If your issue is with a theme not working that you purchased somewhere, contact the author of the theme and let them know you’re having issues.
I know this doesn’t exactly answer your question but if you clarify exactly what you’re trying to do I could try to help you out further.
– Freddie
