To Iantimmy123- There's a few ways of doing it, but they all involve triggers. Triggering one thing will spawn a certain path, while triggering something else spawn another path.
In terms of map transitions, at the beginning of a new map, there has to be something, I use a dialogue, to automatically trigger the path you choose in the last map.
For instance, in my mission you can be a diplomat or you can start a war on one map. The next map has an NPC which asks you what happened outside (the p[revious map). Then you get two options. 1. All is well. I think we have peace. This choice opens the peace path. Or 2. I think I started a war, which triggers the war path.
I hope that helps. In terms of the nitty gritty of actually doing that in foundry, I suggest looking through the various tutorials made by StarbaseUGC.com