Backing,
With baiting, you have to develop a bit of a social intuition via experience to understand how this works and how to apply it. The idea is to tell a girl a little bit about you and to slowly and gradually unravel who you are over a long period of time, without 'showing all your cards.' You want her to invest as well, and by making interesting statements without explanation, she'll naturally be inclined to ask you questions about your statement(s). For example, you could say, 'Hey Susy

, sorry I've been radio silent the past few weeks, I just came back from this cool trip!' So assuming Susy likes him, she'll be thinking, 'So that's what he's been up to! I wonder where he went, what he did, how long he was gone for, why he went, what was so cool/great about it.' She may not think all of those, but that goes to show you some of the possible questions she'll want to ask.
Think about it, if a girl you liked sent you that text, you may be a bit curious about her trip, and want to ask a bit more about it. People are naturally curious so making a vague yet intriguing statement allows the girl to want to invest and learn more about you.
Hope that helped,
Garrett