Page Width

Hi I am hopeless with technology and don’t know how to code…however I’ve got a website http://www.chexle.wordpress.com and the text on the site is really centred – I’d like it to be across the width of the whole page. I’ve seen that there are other posts about this on here but I can’t work out how to input the code – on the html bit of the editing page the width isn’t displayed anywhere to edit.
If someone could help that would be marvellous!
Thank you so much,
Holly