To install a WordPress theme, please follow the steps below:
Export your WordPress theme from Artisteer as a zip file;
Log in to your WordPress administration panel and select Appearance -> Themes;
Switch to the "Install Themes" tab (in WP 3.x) or select "Add New Themes" (in WP 2.8, 2.9);
Use the Upload link in the top menu to upload and install a zipped copy of a theme exported from Artisteer.