If you give some more details of when and where you want to travel it will be easier for you to get help from the Community. 

What planning?

Start with spending a few minutes and read the basic info on site-the usual 1st time Qs are all answered there-and even more. This should be evident

Planning for train times- best site is bahn.com./de as it covers most of EUR, but not all.

DO note-seeing youre name, that currently, as far as latest info has it. there are very few or NO trains at all over borders in Balkan (and what runs is very cheap anyway) and also hardly any on TCDD IN TR-only the hi-speed to Konya/Ankara. But maybe your family knows more as they likely live there?

It IS possible-but with detours- to reach TR from DE by train, but it will take at least 3 nights in a train. The last leg-Sofia_IST (Halkali only!) only runs summertime.

Thank you for your interested