I really can’t understand how it works. My action bar looks like this.
But in a lot of people’s videos, it looks like this.
2. Bear form / Cat form / (Flight form/Travel form) / Moonkin form / Tree form / Travel form.
The problem is that with my buttons. I can’t split from the flight to the travel form.
Please help me 
Flight is travel form?
It will be your stances, a druid has stance numbers. I’m not in game to look atm and I’m useless at macros but each stance has a number , for example stance 3 = cat form or stance 4 = travel form, stance 5/6 = flight/epic flight form and so on. You will be able to make a macro for either of them, something very basic like /cast Swift Flight Form and bind it to a button. Other ways include using the stance numbers but like I said, I’m totally useless with macros but simply using /cast Swift Flight Form should do a job for you. If not, I’m sure someone who knows their onions with macros can help you out.
What you are looking for i’m assuming is the tome of the wilds which lets you learn a separate travel form that is exclusively a ground form that lets you carry someone else, and is a separate key bind from travel/flightform. you can purchase it from moonglade from Lorelae Wintersong or in dreamgrove from Amurra Thistledew. tree form is also another tome of the wilds book that you can buy from the same two vendors that you can learn, it is purely cosmetic.
and obviously moonkin form is now a balance exclusive form so you won’t have it unless you are specced into balance