First go to Undernet 3. Then go around the square untill you get to the top of the square.
Then you'll find a small road down. Go down the small road that leads to a square and go
around the square untill you find another small road that leads to a warp point. Go in the
warp point and when you come out of the other warp point leave the square and walk around
untill you come to another warp point. Go into the warp point. When you come out of the
other warp point you'll see a road. Follow the road and it'll take you to Undernet 6