Complete Newbie needing help please

Okay so I'm brand new to this, I've never built a website or a shop online.
I have everything installed however when I go to my site there is only the demo open cart page up
Where do I go to customise it and make it my own?

I've seen different youtube video's but they never explain how to get to the open cart editing menu.
Just how to edit.

I bet it's gunna be something so simple!
Thank you guys!

Www.yourdomain.com/admin

And it'll ask you to log in :-)