...
You have the ability to create a Lead Source as well as Sub Sources. You might want to use sub sources to track all your social media in 1 source but then create sub sources to break it down into Facebook, Twitter, PinterestInstagram, Yelp etc.
Select the Setup
Select Marketing
Select Lead Source
Select Add Source
...
Name your lead source
Give your lead source a Description - members will not see this.
You can mark this lead source as Internal which will hide it from members
Lead Flow: By selecting a lead flow, all leads that you assign this lead source will automatically be assigned to the lead flow.
IMPORTANT this is how you can automate the entire lead flow sequence is by assigning all your leads from a specific source to a specific lead flow
...
You can either select Save and Exit or Add Sub Source (for example: a lead source can be Social Media and a sub source would be Facebook)
...