To replace the SCM logo at the top left with your own club logo you first need to upload one.
Go to "Club > Documents" and upload your logo by clicking on the "Add Document" button. You must upload your logo into a non-private club document folder (or one with no permissions assigned to it).
Then go to "Setup > Club > Details" and select the file you just uploaded in the "System Logo" field and click the update button.
The system will resize your logo to fit the space available.
To change the logo that appears on invoices and reports, do the same for the "Report Logo" field.