Ok all you do in Photoshop is create a mockup of what you want your site to look like. Then you have to slice up your mockup to get the usable parts that you want to display on your website, e.g. logo, header, background, navigation buttons etc. The colours and any boxes around areas can be displayed using CSS. (Note I would certainly not recommend using text within your images as per the garysimon tut, text should be in the HTML code, unless you are using some fancy font for your logo)
Your next step is to set up the HTML code and CSS to display your website, your different sliced images will usually be displayed as background images in the CSS for the main set up of your site. You do not need any fancy expensive software to do this part, but you absolutely need to learn how to code in HTML and CSS. Depending on the platform you are using, there are a lot of free text editors specifically for coding and you will also need to download several different browsers to test your site, e.g. Firefox, Chrome, Safari, Opera and versions 6, 7 and 8 of Internet Explorer, as each of IE's browsers behave a little differently. All of the browsers are also free downloads.