1. On the main stage double click anywhere in the background on our layout. This will open the insert object dialog.
2. Choose Sprite (double click it or click it then hit Insert). Name it Wall and click insert.
3. Click on the layout to place the sprite. This will launch the image editor window.
4. Use the rectangle and fill(paint bucket) tools to create your wall graphic. In my case I also used the resize button to change the size of my wall to 64x512. I also used the crop button to eliminate any extra whitespace in the image.
5. Close the image editor window and you can now place your wall image in the layout. You can control click your wall sprite to duplicate it and add multiple. Do this now and add a couple, you can use my example below as a basic guideline. When you place the walls feel free to resize them as needed.
6. Make sure you assign the Solid behavior to the walls. Select a wall in the layout, and in the properties panel on the left click behaviors and add the Solid Behavior:
7. Now we can get to work with adding the proper events to allow our character to wall jump. Feel free at this point to run the project to ensure that the character has the platform movements and that the wall are solid and you cannot jump through them.