How do I progress levels in Doom Builder 2?

So, lately, i've been building maps in Doom Builder 2, and im trying to transition between each of my custom levels like in the actual game. I already know how to exit the level with switches and all that, but I'm still stuck on playing on all my maps in one game, instead of having to exit the wad, and opening the next.

Just hoping anyone who uses Doom Builder 1 or 2, can help me out. thanks!

The levels need to be saved in the same wad. When you make the level, Doom Builder asks for the level name (Map01 or E1M1 by default). You'll need to go to edit>map options (or press F2) and change the level names to what level you want them to be (Map02, E1M2 for instance) then go to file>save map into..., and save them all into whatever wad file you want them to be a part of.

Thank you very much!