I tried opensuse for a time and I really like how dolphin is in firefox and don't like the GTK file manager at all.

My problem is, that I want that same functionality on Slackware.
Looking at the Archwiki for a little help with getting a KDE filemanager integrated in firefox, I went to the upstream site here https://build.opensuse.org/package/s...MozillaFirefox.
Except now what am I supposed to do?
Do I just download each indiviual file and figure out how to compile it?
How can I or someone with little knowledge of how to compile something like this do so without some guidance or a README of some sort?

I think for the Dolphin integration you only need this KDE patch:

https://build.opensuse.org/package/v...patch?expand=1

So you can use the source file from Mozilla, apply the patch, build it, done.

Any place I could get some help with that?
Never compiled FF or applied patches.

What schamtzler pointed you to is a diff file. You apply a diff to the source files using patch. "man patch" for the details.

"patch" is a useful command to know, & this is as good a time as any for you to learn it. Take a moment first to save a copy of the original code because it may take you two or three tries to properly merge this patch into the source. (Unless you're smarter than me: the first time I used patch it took me several tries before I got it to do what I wanted.)