Yes, this is pretty simple stuff but the NX is a little particular compared to some of the other bikes I own (or have owned).
Tools: 1/4" drive ratchet, 12mm & 10mm sockets, 1/2" drive ratchet, 15/16" (or 24mm) socket, oil drain pan, funnel and paper towel or rags.
Use the 1/4" ratchet with 12mm and 10mm sockets to remove the engine pan. The 12mm bolt is at the leading edge of the pan, where it meets the frame. The 10mm bolts (2) are at the trailing edge of the pan. At some point you may consider replacing the hex bolts with Allen bolts. Allen bolts have a tendency to maintain their internal hex shape even if they come in contact with a rock or a curb. If a hex bolt's head is rounded off, it may take a vice-grip to remove it.
Use the 1/4" ratchet and 10mm socket to remove the pinch bolt from the shift lever. The bolt has to be completely removed from the lever before the lever can slide off the splined shaft. Make note of the location of the tip of the shift lever in relation to a fixed point on the engine. You'll need to put the lever back in the proper location so that you can easily shift gears. The splined shaft allows the lever to be replaced in different orientations.
Inspect the screen for debris. If there are metal chips you may have more serious issues to address. Be sure the screen is clear. Replace the screen, spring and plug as an assembly. It can be a little difficult to try to push (against the spring) and get the threads started. Be patient and use an extension (3") with the socket, if necessary. Tighten the plug so that it's good and snug but not overly tight. You don't want to strip those threads. I have to use an offset funnel to fill the sump because the fill hole is very close to the frame. Replace the shift lever and engine pan. Inventory your tools to ensure you didn't forget something. Properly dispose of your drain oil (most auto parts stores recycle used oil - my local Auto Zone still does). Start the engine to be sure everything is OK. Other maintenance things to consider while changing the oil: clean the air filter, clean & lubricate the chain, check tire pressures and/or lubricate frame pivots.