Welcome!
Cell phones are pretty locked down so unless its rooted your likely not going to be able to change the DNS server settings for your cell carrier connection. You can for you home wifi though. The following looks right. However if you let us know the domain that is not resolving we can take a look and try to figure out what is wrong. If the issue is the DNS service settings you can likely change your connection to fix it, if wifi disable wifi to see if you cells DNS settings work, if your on cell see if a wifi works. If both are having issues then its likely an issue with the DNS settings for the domain your trying to navigate to.