Struggling to center and align elements that contain text

I”m using the Post and Page builder with the WPOcean theme. I don’t understand how to center elements that contain text; I’m trying to take a line of text and center it across the page. I’ve tried changing the padding and margins but I don’t understand how they work combined with the given width of the column that my text sits inside of.

Occasionally I’ll get something to look correct on my desktop screen but when I click on the tablet or phone view, my text runs all the way down the page in a one-letter-width column; the letters are placed on top of each other in one narrow vertical line.

I’m working with the home page that I was given when I chose the WPOcean theme. In trying to customize it the way I want it to look, am I running into so many problems because I’m trying to customize it too much?

I’m finding using the Post and Page builder to be really difficult and I don’t know how to find answers to the problems I’m running into.