After activating the plugin go to the settings page. There will be a set of tabs for you to use. The first tab is labeled Background. On this tab you need to set the default width and height for your captcha images. Next select whether you want the background to be a gradient or random shapes. A gradient background shades between colors in the number of vertical lines across the image that you select. Random shapes draws the number of random shapes in the background that you select. Finally create the colors you wish to randomly use in your background.
The second tab is labeled Font Settings. On this tab you will set up how you want your characters to appear. You can specify a specific set of characters if you want it limited to just a few or you want only numbers for instance. Next enter the number of font files that will be used to randomly select from. Check the checkbox next to Case Sensitive if you want the entered captcha to match the case of the characters in the image. Otherwise they can be upper or lower case and still be accepted. Finally create the colors you wish to randomly use for your characters. You should use light colors for fonts and dark colors for the background to create some contrast. But you are free to set it up however you like.
The third tab is labeled Upload Fonts. This is where you upload your font files to be used in the captcha images. There are a few fonts included with the plugin but you can upload as many font files as you want to make the characters in the captcha images more random.
The fourth tab is labeled General Settings. Here you will find a few options related to the general behavior of the plugin.
Request key: This is the string used in the URL to identify a captcha image request. this should only be changed if images are not showing up.
Add To Comment Form: Should a captcha be added to the comment form?
Add To Registration Form: Should a captcha be added to the registration form?
Add To Login Form: Should a captcha be added to the login form?
Add jQuery To Header: Some themes do not contain jquery. Check this box to add jquery to the header.