Many of the functions of Stig's Sky Calendar is dependent on knowing your approximate location to calculate the correct data, there are two ways you can do this.
By quickest option is to click on the GPS icon in the app bar, this will request your geographic location from the browser (you will have to accept to share your location with skycalendar.com).
The other option is to select the Location option from the menu. Here you can use the map to set your location. Zoom out until your desired location is visible, then drag the pin to that location. You may repeat the process until you are happy with the accuracy, pin-point percision is not required for any of the functions in the calendar.
After setting a new location use the Save Location button to save your setting so you don't have to set them again the next time you visit. The data is stored on your device using web Storage and not on our servers.
From the Location view you may also change the name of the location, modify the timezone and turn on/off daylight savings.