I Need To Point Another Domain To An Existing Site

Hello!  I have a website, www.myxtremeleads.com.  I recently purchased another domain name, www.xtrememobilemarketing.com and need it to point to my Homestead site.  At this time, I can't just change the association because I can't have any downtime as this is where my clients login and access my marketing system.  How can I accomplish this?  I don't care if BOTH domains go to the same site, in fact that would be kind of optimal, but at the very least, I need my 2nd domain to go to my Homestead site.  Please advise :)   Thank you!