The Dropdown Redirector Web Part is used to refer to a sharepoint list that contains a list of sites and their url that you would like to redirect users to.
Prerequisites for using this Web Part: A list containing at least 2 fields, Website name and a url to redirect to.
To add a Dropdown Redirector web part to your web page, you need to select it from the Add a Web Part button while in edit mode on the page.
Select Cmich from the Categories box, and Dropdown Redirector from the Parts box.
Click Add to add the web part to your web page.
To configure the web part, click the downward arrow on the right side of the web part and select Edit Web Part
You will then be presented with a configuration box on the right side of the page.
The Appearance section is currently expanded, you can adjust the appearance to your liking in this section. Once you are done with that, click the + next to the item you wan to edit. The Appearance, Layout, and Advanced sections are for changing the look of the web part and can safely be ignored while you are setting it up. The main web part settings are in the CMU section. Click the plus next to CMU to expand that section.
This is where the actual settings for the content of the web part are controlled. The default text field is what is displayed at first before a selection is made, the List Name field is the name of the list with the sites and url's that you want to appear in the redirect dropdown. The Dropdown Text Field name is the name of the column in the list that contains the site names you want to display. The URL Link Field Name is the name of the list column that contains the url of the site you want to redirect to.
See the top of the page for a small example using a simple 2 item list.