How to Create an Adjustment Layer
To create an adjustment layer, go to the project media tab.
On the lower right-hand corner of the panel, click on the New Item button
There will be a menu of stuff to click. Click on Adjustment Layer
Click OK
Now there will be a new adjustment layer in your project media bin.
Drag it onto your timeline and now you have a new adjustment layer where you can make adjustments without affecting the original video!