From your homepage:

1. Select  + Add Challenge or Add Activity button under its respective challenge section. 

2. All eligible challenges will be listed on the left-hand side, use the checkbox to the left of the challenge banner image and select "Save".

4. If it is a personal challenge, you will click "Next," then select the start date before using "Save."

5. Once saved, the tile will appear in your challenge section.

**For more information on the challenge you are participating in please see How do I navigate a challenge (more info)?