Please follow the procedure below:- 

1)Create Your Campaign 

2)On Preview Page , Check Option 1-Share on social networks

3)Click on Social share site icon on which you wan't to share your campaign 

4)New pop up window will be open.

5)Enter Your account  Login Details 

6) Click on Share button

7)Your Campaign has been share on your account

8) Example ->How to share on facebook