Help with trains colliding

[Spider2k9]

Hi guys. Having a bit of an issue with my trains. Basically they keep crashing into each other at one of my cross sections and was hoping there was a way to stop this happening?
Ive tried with signals but had no idea how they worked so hoping someone can help me.

Thanks in advance.

[Smarty]

You need to place signals at the spots of the red arrows

[Kelderek]

I don't see any rail or chain rail signals in your screenshot at all. You need these signals at every intersection of tracks. If you are unfamiliar with their use then I suggest you check out this train tutorial video:
https://www.youtube.com/watch?v=3ZiL7_vfJtQ