Transferring over site from a Development area to a Live area

I need help to transfer over my website from a development area

https://www.knssconulting.com.previewdns.com

to

https://www.knssconsulting.com

I am very new to www.remarpro.com and I was told to develop my site in one area before it went live and then transfer it over to a live area. But I know all the links, images…etc Have the development area URL’s and pointers.

How do I transfer the site over and not lose everything I worked on and be able to update the URL’s, pointers, images…etc

Thank you,
Brandon