1) On the dashboard click on "Campaigns" under the "Tools" section on the left.

2) Click on the Call or Sms  button depending on whether your campaign is a SMS campaign or Call campaign

3) You will need to fill in the Flow name , Caller ID , Campaign Type  and  List of numbers in addition to time of the campaign 

4) Save the campaign by clicking Add

PS: If you want to send a transactional SMS campaign, you need to create a transactional SMS template  and choose it in the "New campaign" popup. This page  has more information about how to create sms templates.