Sure, here's a step-by-step guide to setting up a redirect to add the "www" prefix using Namecheap:
1. Log in to your Namecheap account.
2. Go to the "Domain List" section and find the domain name you want to set up the redirect for.
3. Click on the "Manage" button next to the domain name.
4. In the "Domain" tab, you'll find the "Redirect Domain" section.
5. From the "Redirect Type" dropdown menu, select "HTTP Redirect".
6. In the "Redirect to" field, enter "http://www.yourdomain.com" (replace "yourdomain.com" with your actual domain name).
7. Make sure the "Forward Parameters" setting is set to "Do Not Forward".
8. Scroll down and click on the green "Save All Changes" button.
Note: It may take some time for the changes to propagate across the internet. So, the redirect might not take effect immediately.