There are several ways to redirect or forward a URL.
Typical 301 redirect
Go to cPanel and click Redirects. This is also known as 301 redirect.
Search engines, like Google, prefer 301 (permanent) redirects. Don't worry, the redirect can be changed and erased.
The 302 (temporary) redirects are less favored, but behave no differently than 301.
Read more in the related article URL redirect, how to create.
To force the www, you need to use Apache Mod Rewrite, not a 301 redirect.
Masked Forward & HTML Forward
Visit this site to create either.
Note: You can accomplish something similar to a masked forward in cPanel. This is known as a Parked domain, and will show the parked domain name in a browser address bar, while showing your primary domain's web site.
Custom .htaccess redirects
You can add coding to your .htaccess file to customize rewrite and redirect rules. This is an advanced method which is not supported by HostGator.
A beginner's example of a .htaccess redirect.
A handy tool which generates .htaccess code for you.
Example codes offered by HostGator.
Advanced Tips
How do I redirect my website to another ip, but still keep my email here?
You must customize your A record. This record controls where you domain's website is hosted.
How do I redirect my subdomains to another site at the DNS level?
This is done with a CNAME record. This record controls each subdomain name like www and mail.domain.com.
How do I redirect my emails to another server?
You must customize your MX record. This record controls to which host your emails will be delivered.
However, when I go to the dropdown menu under redirects in cpanel it doesn't show domain it only shows domainvideo