One of your first problems is the chain signal on the wrong side of the track in the lower right (see yellow X below), that needs to be removed. Based on the way you are doing this track all your signals need to be on the right hand side of the track in the direction of travel. Since your track ...

I have watched a few videos on signals and each time think I get it, but I can never get the simplest thing to work correctly in all situations.
To perhaps finally have the penny drop, could someone please help explain what signals I need in the below to allow trains to travel freely in the upper ...