Glad to have you join the QuickBooks Community. I'll be happy to give you a hand with switching from QuickBooks Self-Employed to Online.
To get started, you'll have to download your Self-Employed data and manually transfer it over to the Online version. Here's a helpful article that shows you how to: Export transactions in QuickBooks Self-Employed.
In order to successfully upload your data into QBO, I recommend checking out the following article as it shows you how to: Import Data into QuickBooks Online. You can also look into using third-party data migration apps that you can search for on our app store by visiting www.apps.com. I recommend choosing an app that suits your business needs based on the app description and the reviews.