Newbie question - stretching the text on my webpage

Hi

New here and trying to improve my website. I currently use the Mr Site package and all the html I have placed in myself, but eventually want to move off to a more professional designed site.

Anyway wonder if anyone can help me - I am trying to 'stretch' my borders / text on my site so it less centred on the page. Not sure if this is the stylesheet?

Can anyone recommend html I can use. My website is www.positivestart.co.uk for example