Choose one or more maps from the right tab and drag it in the right upper corner.
Use the opacity slider to set the transparency. You can change the order of maps by dragging them up/down on the right side of the tab.
Different views are available for chosen maps to get the best results of your research.
Use the share button in the right upper corner to show your work to others: directly or via social networks
Refine the position of a map overlay with the Georeference tool. It is even possible to upload your scanned maps.