Log into our game control panel and navigate to your server.
Stop your server.
Click the Command Line Manager icon.
Click the Customs Command Lines tab
Click edit on your custom command line, If you do not have one already created, click the +New button to create a new one.
Add +host_workshop_map XXXXXX to the additonal Settings option, replacing the XXXXXX's with the WorkshopID of the map.
Example: +host_workshop_map 3070290869 would be what you would use for https://steamcommunity.com/sharedfiles/filedetails/?id=3070290869
Click the Save button to save your changes.
If this is a new custom command line, press the Select button on the right-hand side of your custom command line to make it active, it will say Selected once it is selected.