1. Add a Content Editor Web Part to the Main Page of the site.
2. Modify the Web Part and click on Source Editor.
3. Paste in the following code while changing the URLs to match your target.
Redirecting you to the new location. If you are not redirected, click <a href="http://sharepoint">HERE.</a>
4. I set the redirect time to 0, but you can set it higher if you like. 1 sec = 1000, 2 sec = 2000, etc.
5. Save the code changes.