Once you have connected your account to Acumatica, you can begin exporting your projects.
To export a project:
Open your project to the Overview page
Under Additional Tools, click "Export to Acumatica"

When you export a project, it will sync any changes from Acumatica since the last sync. Upon success you will see this:

If any items in the project are not found in Acumatica, it will show you a list of those products:

These items will need to be added manually using this method.
Hope this helps - let us know if you have any questions!