Error while trying to create admin user

i have installed owncloud in Ubuntu. I am a Beginner in Linux. The following Error come at the beginning:
Error while trying to create admin user:
Failed to connect to the database:
An exception occured in driver:
SQLSTATE (HY000) (2002) Connection failed.
i have try to log on with root and with my Name harry, but always i have got this Error.
Where is the Mistake?
Who can help me?

please check your database ( mysql or another DB that you are using ) and be sure that your credentials are true ,
hostname , password, username , db name ,

thank you for your Answer.
Like I said, I am a absolut Beginner.
Do you want to help me to solve my Problem Step by Step, only you have Time for it?
I have create my Database with mysql /phpmyadmin.
But I don’t know where I can find a conf. file for it.


P.S. sorry for my bad english, I have learned it in School 45 years ago.

Owncloud does not need config file for editing on startup , you can access it by installer ,
but , if you need some config , you can go to config/config.php and edit what you want there .