@wolfcry911 is right. I think the quote just ended up going to far.
Your text alignment isn’t an issue. It’s the floating of the container (#main) that is causing the issue.
border-right: 1px solid rgb(152, 152, 152);
float: left; /* <
This is what they were getting at */
It also looks like it happened because you deleted the CSS file from the Home page. It’s on the about us page.