Can anyone help me figure out how to use jmeter and force it to fill out and submit a form automatically? For example, I need to fill out the google search box and then click the I'm Feeling Lucky button?
Is there a reason why you want to load test Google? If you just want to have a script that tests the functionality of a Website, try selenium: http://seleniumhq.org/. If you are actually trying to load test a form, you have to create the appropriate request. Using a tool like Fiddler can help.
Google is not a good example because it uses GET for the form. For example, to search "jmeter" and press Feeling Lucky button, you can just send this URL,
http://www.google.com/search?hl=en&source=hp&q=jmeter&oq=&btnI=1
To do a real post, you need to find the form control field names from a trace or by looking at HTML source and just do something like showed here. The username/password are the field name to post. The action is http://www.example.com/login.
Please note the screen shot is wrong. The method is a "GET" and it should be set to "POST", otherwise the form will not be submitted properly.