Short answer, very easy. Long answer, Veeeeeeeeery easy.

I had a free theme installed form the Wordpress built in theme gallery I think. It was OK but a bit dull. I chose it because my Spanish Examples site will be more of a slowly growing reference and resource site built using pages, rather than a regular blog. I have included a blog (covering my own progress learning Spanish), but it won't be the main focus of the site. Lots of the cooler themes are made for blogs with regularly updated posts appearing on the front page, but there are free Worpress themes out there which are designed to manage pages like a Content Management System (CMS).

Anyway, a friend sent me a link to his new page and I liked the theme he was using, and it was free too so I decided to swap. Don't worry about changing between Wordpress themes, your writing is always saved. You may have to tweak a few settings to get everything looking nice again but essentially you can experiment a bit without worrying too much.

My new theme is called Arras, and there are two versions. The one I am using has a rotating carousel display on the home page which displays various posts or pages, plus a nice customisable layout for the rest of the page. There seems to be an active community of users plus a forum to help answer any questions, and the developer seems to be actively looking after things, so I felt confident that if I got stuck I would be able to unstick myself without too many problems. Well I have had a few configuration issues, and I still don't understand quite how to get exactly what I want, but it's servicable for now. I will need to get some images together as well, which is good as I like my photography and should have a bunch of suitable photos already. The site is slowly looking nicer.