Databases

I am a beginner and trying to add a database to my project.
I've been following afew guides that approach it in slightly different ways.
However, each attempt fails to save tables. (Example Guide)

For some reason, I can't even name the table once set up.
Even after saving file, when loading it to an application, I receive:
"The database you selected is new or does not contain any objects..."

What am I doing wrong?

TIA for any insight.