1) You can learn CSS and do it from scratch. CSS and PHP are the basic building blocks of WordPress. There are other technical languages you might want to pick up as well. A good place to start learning CSS and PHP is at ThinkVitamin.com
2) You can design a mock-up of your website in Photoshop or other creative type software or even draw/paint and then scan your work. Once you’ve created a picture of what you want your template to look like you can send it to a designer who can cut it up into pieces which can then be used to compose a wordpress template you can easily use.
3) You can simply pay a designer to design the wordpress design for you, although this could prove to be costly depending on whom you hire and how much work needs to be done.
4) You can design your own wordpress template using Artisteer without touching a bit of code. Artisteer has a nice what-you-see-is-what-you-get interface that makes designing your on wordpress template easy and fun.
5) If you are a windows user you can use an Adobe Photoshop plug-in called Divine that will cut your design into a wordpress template for you. Right now there is only a windows version of the plug-in. I am eagerly anticipating their mac version of the plugin..
