The transport block is located directly in your project, just after the accommodation:

You'll be able to save them under different category headings depending on the type of transport. To do this, go to your settings, to the Custom fields tab, then select Steps, and here you can add different categories:

In each category you can add information of interest to you, which you can then add to your documents:

By default, information is already entered in your "Flight" category, which simplifies the process of entering flight information:

You can of course add other custom fields.

All you have to do is fill in the information directly when you create your transport step: