You will need: 4 fences, four flower pots, some camp fires depending on how long and wide your bridge is, 1 water bucket, some spruce stairs, and some spruce slabs
Step #1: build a strait line over the area you want to build your bridge with your camp fires. Then, use your water bucket to distinguish your fire.
Step #2: Put your fences on both sides of the bridge with your flower pots on top.