anyone who knows it better feel free to add tips and corrections

step 1: i made a map with 2 regions, farmland and ghosthouse.
after a while i created nodes that i wanted to connect at more or less random locations on both regions. i used 2 8x8 floor nodes to do it, because i read somewhere that one should use more than 1 node to stitch.
step 2: adding stitch doors.
after some not so successful attempts i opened the ghosthouse region and highlighted one of the doors i wanted to connect. then and opened the node properties window and switched to the stitching tab.
here a stich ID has to be entered. i decided to start with 0x0000001 and go up after that.
next the region has to be set to the TARGET region, the region the node is to be connected to. (not much of a choice on my map)
then i hit the ok or apply button and did the same for my other 3 doors.