When I am editing my maps they confuse me because they just pop?
I'm not sure what you mean with "just pop." But, respawns work this way:
If there is a chance that the player will die on your map, you should consider adding a respawn point at various spots, so the player doesn't have to travel back through the whole map. This can be critical on boss fights. If the respawn is too far away, it can make some players give up, because the mobs fully heal by the time the player gets back to the spot.
Dose walking over the point activate it? I want to block a path behind the player and provide a new spawn.
It works by proximity. If the player is closer geographically to a respawn point, then that becomes the respawn point if they die. So, it could be in front of where they die. So long as you put a respawn point on the other side of the wall, it should be fine.