You can direct your players to go to your website and join your events through the events tab which will be displayed in date order as below.
They click in to the Team challenge event which they would like to participate in and then select from the events details page which activities to book on to. They get placed in the basket at the top of the page and to continue with the booking they simply need to select 'Book now'
The booking form is produced where they can complete their booking.
The other place where you can direct your players to book on to your Team challenge event is the campaign site for the events which is: https://clubspark.lta.org.uk/TeamChallenge
The only additional step is that they would need to do an area/postcode search to find the events close to them.