Adding custom elements to a theme with OOP

Hey guys,

I would like to ask this as a general question. When you have a theme and want to add custom elements to it such as an additional image somewhere in the header etc. you go to header.php and locate the area where you can add the html for that.

But I’m using Beaver builder theme which is written in classes or object oriented programming and I find it extremely hard to locate the areas in the files where I should add new html code for custom elements I would like to add.

What would you recommend me do? I know that it’s a general question, and I do know some OOP, but to understand tons of line of code that others wrote it’s a bit overwhelming.
Maybe there is another way? I tried to use solely CSS with psuedo element of :before or :after, but it’s too limited.

Thanks in advance,
Omer