How can I use yahoo mail on outlook?

How can i email someone on craigslist without getting a error because ms outlook i want to use yahoo mail?

• when i try to respond to an ad ms outlook automatically comes up and i get a error i want yahoo as my external mail

• Answer:

  that just means that outlook is your default email program. Here's how to set your yahoo as default Step 1 Log in to your email account from Yahoo's home page. Find and click on 'Tools' at the top of the page and select 'Internet Options.' Step 2 Select the 'Programs' tab in the Internet Options window. Select 'Yahoo Mail' in the email section. Click 'Apply.' Step 3 You have now successfully set Yahoo Mail as your default email address, and any time you click on an e-mail link, it will automatically open a new message in your yahoo e-mail. Hope this helps!