The following is a quick overview of how updating Domain Name Servers or A (ie. @) Records works.
Firstly, if you don't already know this...a domain name is sort of like a contact name in your phone - there's a number associated with it, but you almost always just search by name - and if you lost your phone, you'd probably have no clue what 90% of your numbers were. That's what domains are essentially - contact names for websites, but the original way to reach the website is with the IP address!
Basically, you update domain name servers or A records (ie. @ records) by logging in to the company (usually what's called a Registrar) you purchased your domain from. They should have some sort of Domain Management Tool or area. If you purchased your domain from GoDaddy it's very easy - simply follow the images below (and if you didn't these screenshots may help you figure out what to look for in your registrar's dashboard.
Updating your nameservers is one way, but you can just as easily also update your A Records. All you have to do is put in the IP Address of where you want to "point" your domain. Pointing your domain allows it to sort of "link" up with the files you want to show your site. So since we will be hosting your ThinApp, you simply point your domain at us! Or, rather at our IP Address! And make sure you hit save when you're done. Usually it can take up to 24 hours to "propagate" (ie. cycle through the whole internet), but it's usually pretty immediate/instant after you update your DNS that you'll see your site.