- Click on the https://developer.salesforce.com/
2. you can navigate to the below form
3. Enter the relevant information and click on the Sign me up button.
4. Check your email to verify the password.
Click on Verify Account button and set your password. Once you have set the password you will be able to login to the Salesforce Lightning User Interface.
Good Luck!
for more details: https://developer.salesforce.com/