Here are the steps to do a valve adjustment on a 2000 Honda Civic DX:

1. Start by warming up the engine to operating temperature by running it for a few minutes. Then, turn off the engine.

2. Locate the valve cover on the top of the engine and remove it. This will expose the valve train and the camshaft.

3. Using a feeler gauge, measure the gap between the valve stem and the rocker arm for each valve. The correct measurement should be specified in your car's service manual. If the gap is outside of the specified range, you'll need to adjust it.

4. Loosen the lock nut on the rocker arm with a wrench.

5. Use a screwdriver to turn the adjustment screw in the rocker arm until the desired gap is achieved.

6. Tighten the lock nut while holding the adjustment screw in place with the screwdriver. Be careful not to move the screw while tightening the lock nut.

7. Repeat this process for all of the valves.

8. Once you've adjusted all the valves, reinstall the valve cover and tighten the bolts to the specified torque.

9. Start up the engine and listen for any unusual noises. If everything sounds good, shut off the engine and recheck the valve clearances to make sure they're still within the specified range.

10. If the clearances are still within range, you're finished. If not, you'll need to repeat the adjustment process for any valves that are still out of spec.