Power BI desktop is the local version, where you can design your reports. But, in real-time, you have to share your work (reports) and dashboards across your organization. For this, you need a Premium license. However, you can try Power BI Pro for 60 days trial, and let me show you how to register for Service.
How to register to Power BI Service
First, go to the official Microsoft website by clicking this link Try Pro. Next, click on the Try Free button to start your Power BI 60 days trial.

Clicking the Try Free button open Get Started window. Here, you have to provide the company email id. Remember, it won’t accept your personal email like Gmail.
Once you click the Sing up button, it sends a verification code to the email that you provided. You have to use this verification code on the next screen.

Next, fill these text boxes with your personal information.

Now you can see the workspace.
