Hey manisha-kalsi,
Congrats on becoming part of the QuickBooks Online family! I hope you're enjoying the simplicity it adds to your bookkeeping, and taking advantage of the great time-saving features. There are a few ways to bring information from the Desktop versions into the Online system, and I'll be happy to guide you through those.
If you're able to open the backup file using the Desktop version, you can actually send the data to Online in just a couple simple steps. Simply press Ctrl+B+Q, then select OK to open the export window. Alternatively, check out this awesome guide to get our data migration team to transfer the file over for you: Import from QuickBooks Desktop and other software to QuickBooks Online
Hope this helps!