Login to your RLSS UK account (powered by tahdah), go to the ATC you have previously created the session against, and click 'Ongoing Training'.
Find the session you want to complete by scrolling down the page and clicking 'Complete' on the session below the wallchart.
In the completion screen enter the 'Name of Trainer', 'Society Number' and the 'Completed Date', before clicking the 'Complete' button to confirm competence.
The training session will now appear in the wall chart showing the completed date and the session short code.