How to create a profile in firefox for selenium.

If you are worried about how to handle CAPTCHA and firefox certificates.
Then use firefox profile for solving these problem.
Below are the steps for same.

1. Make sure all your firefox instance are closed
2. Click Start>Run
3. Type “firefox.exe -ProfileManager -no-remote”
4. Select “Create Profile” (i.e. selenium)
5. Click “Next”
6. Enter new profile name
7. Select a directory folder to store your new profile
8. Click “Finish”
9. Select “Don’t ask at startup”
10. Click “Start Firefox” and configure settings based on suggestion below***
11. Set Profile back to “default” (enable you to use your previous settings on your browser)
*** Suggested settings for your Selenium Profile
1. From “View\Toolbars” tab, uncheck “Bookmarks Toolbar”
2. Right click from toolbar and click “Customize”
3. Remove “Google search” by dragging it to the “Customize Toolbar” window
4. From the “Customize Toolbar” window, click “Use Small Icons” check box then hit “Done”
5. Click “Tools\Options” then set the following:
a. “Main” tab
- set Home Page to “about:blank”
- uncheck “Show the Downloads..” option
b. “Tabs” tab
- Select “a new window” for new pages
- Uncheck all warning options
c. “Content” tab
- uncheck “Block pop-up” windows option
d. “Privacy” tab
- uncheck all “History” options
e. “Security” tab
- uncheck all “Security” options
- click “Settings” and uncheck all warning options
f. “Advanced” tab
- Uncheck “autoscrolling” option from “General” tab
- uncheck “warn me …” and “Ssearch Engines”option from “Update” tab
7. From the address bar type “about:config” and add the following by right-click anywhere on the page and selecting “new”
- extensions.update.notifyUser (type=boolean; value=false)
- extensions.newAddons (type=boolean; value=false)

For more details refer following url:
http://kb.mozillazine.org/Creating_a_new_Firefox_profile_on_Windows