The feature is automated - so generally you do not need to do anything, however, if you would like to move the current Active Claim amount to the Ready to Claim tab in order to then perform a manual submission, all you need to do is:

From Financial > Gift Aid > Active Claim, click on the button to the right of the Active Claim screen that says 'Move Claim to Ready'. This will then move your Active Claim to the Ready to Claim tab.

If you can not see this, then your Gift Aid settings are not set to Submit Gift Aid Claims to HMRC as per Gift Aid - Getting Started

or you have details in your Ready to Claim tab.  To manually move your Active Claim to Ready to claim the ready to claim needs to be empty.  If you have transactions in your Ready to Claim tab you will need to submit those first.

Once your Ready to claim tab is empty the Move Claim to Ready will be available