You can quickly add markers to the board from the QC toolbar.
The QC toolbar is in the bottom toolbar of the VASL interface.
To add a marker to the board, click on the marker you want to add, and drag it to the board.
If the counter in the marker toolbar has an arrow in the lower right corner, clicking on the marker in the toolbar opens a popup with a number of options. Click in the popup on the marker you want to add to the board and drag it to the board.