In order to send your domain traffic through Repointer, you must change the DNS records on your domain.
In most case your domain registrar will offer free DNS services for your domains. You can add/change these records inside your domain registrar account.
Option A: Send any and all domain traffic through Repointer
You will need to create an A record for the root of your domain (no subdomain) and a catch-all wildcard (*) CNAME for everything else.
Option B: Send "stray" traffic through Repointer
If you have your website set-up on the root domain and/or the www subdomain, you can use a wildcard record to catch all other traffic (be it from spelling mistakes or curiosity) and redirect it back to your active website.
Option C: Send specific subdomains through Repointer
You may want to set-up your special subdomain as a vanity url or external link manager/tracker. You can set-up a CNAME record for one (or more) subdomains.
Note: Any changes to DNS records will take hours, up to two entire days, to spread across the world wide web. Your Repointer links will not start working right away.