f to fell problem

Hello. Can you give us more information please? Post some screenshots, walk us through the problem so we can diagnose what could be going on. Most likely the fill is causing overlapping faces.

Hi Kareem HHexplaysroblox ,

It is most likely, that your Selection is incorrect. But, as Omar already said, please post some screenshots or so. We need more information in order to help you.

Looking at the image, I don't think you have selected the same vertices as in the lesson. You may want to take another look.
You could have some double vertices causing some of the issues.
When selecting the vertices, take note also of what edges are selected.

Don't panic, the best option here I think is to start over. I can see many other issues in you mesh that will cause problems later.

...and the Bevel Modifier problem is very likely, because you have Clamp Overlap enabled:

Yes! I would say your best option is to start over, delete the console object and start again. You will have a hard time trying to fix these issues, the more I look at it the more problems I see.
It is very common to delete a model and start over, I still do it.

I agree, starting over is the best approach. Your brain will try to complaint and come up with excuses, but tell it to go back to its brain functions and leave the thinking to you. When you're first learning, when you stay trying to fix a problem, you will surely loose more time and only get more confused, it's always better to start over, it's how your mind starts to understand the gotchas and how it all flows.