Our documentation section contains instructions on how to use and customize Gravity Forms. The documentation is setup in a Wiki-style format and is constantly being revised and updated as Gravity Forms continues to add new features and capabilities. You can find all of the documentation via the link in the right sidebar or click through to find it here.
http://www.gravityhelp.com/documentation/page/Gravity_Forms_Documentation
There are a couple of methods to embed your form in your site. There is a shortcode method with a simple wizard to add your form directly into your post content and there is a php function call to allow embedding the form directly into the theme files. You can find information on both methods in the documentation section here.
http://www.gravityhelp.com/documentation/page/Embedding_A_Form
Custom CSS rules for your forms belong at the end of your theme stylesheet. Action hooks and filters belong in your theme's functions.php file. You can find more information in the documentation section here.
http://www.gravityhelp.com/documentation/page/Where_Do_I_Put_This_Code%3F
Usually, the issue is the reCAPTCHA field. A limitation of the reCAPTCHA service is that it is not compatible with AJAX. Gravity Forms automatically disables AJAX if a reCAPTCHA field is present to prevent problems from occurring with reCAPTCHA.
If you want to use AJAX and use a Captcha you can install the Really Simple Captcha plugin. Once you activate that plugin it will add additional options to the Captcha field in Gravity Forms.