I only want to comunnicate with external device and control it.
Yes and you have implemented something that if you have actually wired it up like you say should work. What we are trying to do is to help you test it to see where you have gone wrong.
One way to do this is a loop back test but you have trouble in doing what was asked of you.
Your DFROBOT RS232-TTL Converter should be connected to some pins other than 0 & 1. This should be being driven by new software serial. You say it is not working so a loop back test would rule out wiring problems and software problems.
The DFROBOT RS232-TTL Converter has a 9 pin D-type socket on the end I am asking you to connect pin 2 & pin 3, You might need to have a plug to put the wires on or you can do it on the PCB side.
When you have confirmed that this setup is working you can then go on to investigate other things that could go wrong like a miss match in the baud rate or data format between your DFROBOT and the thing you want to connect it to.