The power is in your hands, you decide how far.
Run or walk the distance you have chosen, it can be accumulated over a series of runs/walks or can be done in one go. There is no deadline so you can set your own goal for when you want to complete the challenge.
Please be aware it does say VRC May Monthly Challenge on the back.
Log in to your account to submit all your evidence together once you have completed the challenge distance. Evidence provided can be a screenshot from any running/walking tracking app or even a picture of a treadmill screen.