Hey;
You have to use science on the hides in your inventory.
step by step :
1. go to the place on worldmap where you wanna set up your tent,
2. click the arrow to enter the isometric view,
3. open inventory
4. hold left click on the hides
5. scrolling menu appears, select the "vaultboy face" icon
6. select science
Ta-daaa. If you have some friends tagging you at the same time, they will be able to see location of the tent.