Hi Thomas,
I'm not sure what's going on with your installation, but it seems that you are not following the recommended Gantry 5 workflow.
Here, have a look at
this blog post. It explains everything in details.
Once you are familiar with the recommended workflow, you might want to have a look at
this blog post as well.
And finally, you should take your time and go through the whole
Gantry 5 documentation in order to be able to build a website with it.
I hope the above helps to get you started. And... Happy New Year