Create a new Salesforce Developer Account And Connect With the Trailhead Account

 Create a new Salesforce Developer Account And Connect With the Trailhead Account:

 1. If you don't have a trailhead account, sign up - https://trailhead.salesforce.com/home

 2. To create a free developer org - https://developer.salesforce.com/signup

 3. Enter details and click the Sign me up button, you will receive a verification email after this.

 4. Open the verification email and click the 'Verify Account' button.

 5. Now we are on 'change Your Password' page. Enter and Confirm the password entered and answer the security question. Click 'Change Password' button.

 6. To connect the developer account with trailhead account, click the profile badge at right top corner of your screen. Copy the link below your name.

 7. Login to Trailhead account and click the profile badge icon at top right corner of your page and then click 'Hands-on-Org'.

 8. Here all the playgrounds are listed. Against the newly created developer account, click the 'Connect an org' button.

 9. Now we are at the login page. Here click the 'Use Custom Domain' link.

 10.Paste the copied domain name from developer account (copied at step 6) and then click 'Continue' button.

 11. Enter the Developer account username and password and click the 'Login' button.

 12. Now, we are at allow access page and here click the 'Allow' button.

 13. Last step is if we want to connect the org for hands-on challenge, click Yes, Save it

 

 You can verify that the developer account has been successfully linked to Trailhead account. (Here we can even set the default org that is whatever challenge we verify next, this org will be selected by default (which we can even change))