I can share a couple of info and steps to ensure you can use your QuickBooks Desktop smoothly, @sinujishnu.

Yes, you can practice and learn the basics of QuickBooks through this website. However, please know you're unable to use the features that require internet access. This is because QuickBooks Desktop 2018 has been discontinued.

Since the program is already installed, you’ll need to activate it within 30 days from installation. If you haven't done it yet, kindly refer to the steps below:

1. Select Activate
2. You'll need to create a login or use an existing Intuit login. If you have an existing Intuit account, select Sign in. Otherwise, enter the information, then select Create Account. Ensure you enter your own information and a secure password.
3. Enter all the required information for your customer account (required field are shown with an asterisk*), then select Next.
4. A confirmation window will appear. For your records, you can print the page or save it as a PDF file.

The detailed process of the software registration and activation can be found in this article: Register and install a QuickBooks Desktop student trial. This includes thorough instructions and screenshots to help you through. 

You can download the student guide through this website: Intuit Education Program. If you need further support, contact our live support to help you get started with QuickBooks through this link: https://www.intuit.com/partners/education-program/contact/.

You can always swing by anytime if you have further concerns with navigating the QuickBooks Desktop student trial. I’ll be here to help you out. Take care.