May be you are using standard domain in salesforce but if you want to register your own domain so here we will learn how to register your domain in salesforce. Salesforce provides a feature My Domain which gives functionality when you register your domain you will add a subdomain to org. With the help of subdomain, you can make your org more secure by restricting the login through it and also highlight your own brand.
Step1: Go to Setup, Select Domain Management then Select My Domain.
Step2: Enter domain name according to your brand and then click on button to check for availability.
After this wait for a while for Register Domain button once it's enabled click to register domain.Edition Domain". Once you receive the email refresh the Registration page.
Step4: Then click on Log in button.
Step5: Click on button Deploy to Users.
Then From Subdomain Log In
Step6: Click on Stepup then Go to My Domain. Then Click on Edit button
Select the checkbox if you want to login from your registered domain.
Your Domain Login Page:
Hope this will help you.