How to fork a bitcoin or altcoin for L&D

[jeeri]

Hi,

I have been trying to find the tutorials, guides for forking bitcoin core or any other alt coins but I'm not able to do it successfully.
I know java, basics of Unix but not C++. I know bitcoin is available with different flavors (technically like bitcoin with java, with c++ etc.).
Could you please help me in starting a full coin development which actually having wallet, working model of coin, mining etc. This is for educational purpose. I want to study about the coin creation.

once I could able to see my own coin I can dig the same in code level.
For creating my own coin, initially  I'm struggling with environment set up.

What are the best sources for creating/forking a coin? How can I accomplish this, I'm looking forward very eagerly for this.

Thank you.

[jeeri]

I have managed to start with the development and code changes too. I'm using VPS with Ubuntu on it.
Now I'm not able to run the QT wallet from VPS. It is saying "Unable to connect to X server". Can any one please help me to fix this issue?