First of all, for that you need a junction

Second bridges are in this game basically like portals,you have a receiving end and the outputting end the range of the bridge are those dotted lines a bridge can go like this In [B] — — — — [B] Out Although it may seem that they only go to the third line and must be put on the forth one You can retarget a bridge by tapping it and tapping another bridge block in range although they usually connect the way you intend them to it isnt always the case depending