If you open a free blog on wordpress.com you can play around all you want and see if you get to where you want. Then open your real site using your own URL on your own hosting account by installing the wordpress backend and replicating what you did on your free site. No-on will see your practise unless you tell them where the site is. Unless you have a lot of time on your hands and are prepared to learn some CSS code I wouldn't try to do it yourself, though. It's not just about building a site that looks representative. You need to be able to make it secure, deal with the SEO, learn how to attract visitors etc.. and the list goes on. Get it wrong and the site will just sit there helping you with very little other than a linkable online brochure. A pro will be able to help you design a site that not only looks how you want but also works for your business.