I have correct python3 program looking like *.py.
I have Digital Ocean(DO) droplet with Ubuntu 14.04.
My program post message to my twitter account.
I just copy my *.py in some directory on DO droplet and run it with ssh and all works fine.
But I need to post message(rum my program) automatically every 15-30 min for example.
Iam newbie with this all. 
What should i do? Step-by-step please!
First install and enable fcron. Then, sudo -s into root and run fcrontab -e. In the editor, enter */30 * * * /path/to/script.py and save the file. Change 30 to 15 if every 15 minutes is what you're after.
Run my python3 program on remote Ubuntu server every 30 min