https://www.allaboutcircuits.com/textbook/direct-current/chpt-10/thevenins-theorem/

 

I tried watching a video but I was confused with the steps? He removed some lines from the circuits then added them together which I tried doing as well.

I did 1750 (series) + 1/1000 + 1/2000

 

Draw the circuit with supply voltage as a short (since it has zero resistance)
The redraw the circuit to see how you combine the series resistors with the parallel resistors to get the equivalent resistance.
You will end up with 3 resistance values in parallel.