A coolant flush is pretty straightforward:
1) Open the radiator cap
2) Open the coolant drain bolt and drain
3) Empty the plastic coolant reservoir
4) Put everything back and fill with deionized water
5) Run for a few minutes and cool down
6) Empty again and fill with 50% coolant
7) Run the engine with the radiator cap off and sqeeze the hoses to burp trapped air
Done