Welcome to the Community, mobilerigrepairs.
You've come to the right place for assistance. I'm happy to provide some info about a Simple Start QuickBooks Online account.
While you can upgrade existing QuickBooks Online subscriptions to different plans, at this time there isn't a way to directly upgrade from the Self-Employed version to Online. To open QBO Simple Start you would need a new subscription.
The following link provides details about the Simple Start Plan as well as how to get started: QuickBooks Online Plans and Pricing
Once you have set up the Simple Start subscription, some users have found it useful to export data from their Self-Employed accounts as .CSV files, then upload to QuickBooks Online.
I'm attaching a couple of related articles that I believe you'll find helpful in this process:
Please don't hesitate to reach back out in the comments below if you have any other questions. I'll be here to lend a hand.