Local server. Local IP vs DNS dynamic

Need Help With My Project
7

found this on https://duckduckgo.com/?q=dynamic+dns+TL-WR841N&t=ffsb&ia=images&iax=images

take a look is easy as that also dont forget to open the port
http://screenshots.portforward.com/routers/TP-Link/TL-WDR4300/Dynamic_DNS.htm