Help with connecting cables

Hello everyone I’m building my first pc and got quite a tough time with connecting cables.

First I had the problem that everyone in YouTube videos has the name of what the cable is for on it labeled but mine don’t.

Then I have a lot of cables over is this normal?

Also I can’t find where the cable named „TKG“ goes to.

And what will happen if I turn it on and some cables are connected false?

I use the gigabyte UD 750w if this helps.

(Please excuse my bad English it isn’t my first language)