Hello Liliana,
It's great to have you with us and I'm excited to hear you're using QuickBooks Self-Employed. I'll give you a few more details about the program so you can get started.
QuickBooks Self-Employed allows you to track mileage, connect to your bank feed, and enter your invoices. From what you're describing, it sounds like you've connected your bank feed to import your expenses into the program. You can learn more about that feature here: Connect you bank accounts to QuickBooks Self-Employed
To make sure you the invoices you need are entered into the program, use the Create invoice feature. There isn't a way to import invoices or income at this time. I've got an article here with more details about invoicing in QuickBooks Self-Employed: Create an invoice in QuickBooks Self-Employed
The awesome thing about both articles I've linked is they give you the steps for both the browser and app environments. Just scroll to the section for the one you're using and you'll be on your way.
If you'd like an agent to help you out, don't be afraid to get in touch. The dedicated QuickBooks Self-Employed team can be reached by visiting the following link and choosing the Self-Employed option: Contact Us
Have a great rest of your day. :)