The best way to build a new skill is to practice it. Try these a few steps in the software.

1. Open Revit 2020
2. Launch Dynamo
3. Create new Dynamo script
4. Add four Point. ByCoordinates nodes to the workspace
5. Define four points in a square using Number nodes
6. Connect points using four Line.ByStartPointEndPoint nodes
7. Change one Number node to a Number Slider node
8. Modify line coordinates with the Number Slider
9. Use Wall.ByCurveAndHeight node to create four walls

Try to experiment with other nodes if you have a few more minutes.