Before going further, if you are just starting with the template, you probably first want to name your site properly.
From the 'Main Menu' at the top of the page, select 'Site Details'.
On the page that opens, fill the form with as much detail as you wish - you don't need to provide full address details, for example.
Update the page when finished.
Having done this there are two routes you may want to take next - the order in which you do them doesn't matter.
- (change the clour scheme, logo, fonts etc)
- Add content to your home page so you can see how things work
There isn't a right or wrong route - you pick and do the other one later!