The buttons are an auto nav block made up from your site tree. If you create a page it will show up there. To change the order you just need to drag and drop in the Concrete5 site tree.

You are free to alter the css for the theme if you prefer the nav to be left aligned.

Thank you! How does one alter the css?

You'll need use an ftp program to view and edit your site files.

In packages/theme_hi_vis/themes/hi-vis/app.css

change:

#page .top-bar-section > ul {
display: table;
margin: 0 auto;
}

to:

#page .top-bar-section > ul {
display: table;
margin: 0 auto;
float: left !important;
}