What is link adjusting and how do I do it?

I have a 2000 honda civic, and my thrid gear never goes in, and also makes a loud scratching noise, on the question I asked before this I got an answer telling me i needed link adjustment, I don't know what that is, can someone tell me what it is and how to do it?
I want to get my civic back on the road!

Youtube it brah

The question should be do you have any linkage and are they adjustable. Some cars have the shifter mount directly on the top of the trans, I don't know if that is what you have or not. But if you do have linkage it would run from the shifter to the side of the trans. Most cars now days don't have adjustable rods but you will need to remove the console to see that. Your problem might be inside the trans.

If only 3rd gear has a problem maybe your 3rd gear synchronizers in the tranny are tailing.