You can post your location and tag friends you're with in 2 ways:
1) Open the main Menu and select Friends:
Then select the On the way tab and select Share:
You will see the following window:
Here you can insert a personal message (optional):
Choose the friends you wish to tag (by click on With):
And by selecting Edit location, you can check into places around you:
2) Open the main Menu, select Meet Up:
Then Share and select either your current location or your destination:
