Alfresco simple invoice approval management system

Hi, I'm implementing a document management system with Alfresco. I basically want to be able to manage the approval of invoices on my company. This is what I would like to have ideally: 1. The company receives an invoice to be paid. A secretary scans it and inserts it on an Alfresco folder. 2. A workflow is automatically assigned to it. The workflow will to the following: send an email notification to employee X. That person will approve the invoice. Then I'll receive an email notification to approve it. When I approve it, the employee Y will receive an email notification to pay the invoice. I have alfresco community 4.2 installed on my server. I'm an IT guy myself, but I got stuck in activiti (eclipse) and would like someone with workflow design experience to finish the job. Extra tips will be appreciated. Thanks