I cant setup two trains on a path

[Andreikone]

I tried to setup a track with two trains to deliver iron, but no matter what combination of traffic lights I try, either the trains crrash or they dont actually go where I want

[Loewchen]

Did you try the train tutorial?
Technically two trains can not go back and forth on a single track no matter the signaling without a bypass.
If you can post a picture of a super minimalistic example of your problem it might be easier to understand.

[Serenity]

For a single track you need bypasses somewhere. Otherwise they will always block each other somewhere.
The more future-proof layout is having two tracks - one for each direction

[Frightning]

Are you wanting 2 trains serving a single pair of train stops? If you build the stops so that they are 1-way rail stops, this is possible with proper signaling, even if the connecting track between them is a single 2-way rail. If you're having issues getting it signalled right, remember that signals go to the right of the rail, relative to the intended path through that rail (2-way rail is created by having paired signals; one on each side of the piece of rail in question).

I wrote a guide to rail signalling a few years back. It's old, but still accurate to how the system works: viewtopic.php?f=18&t=30304