Hi tplee,
We have a webinar which discusses secondary data connections. Typically, what you need for retrieving items from a SharePoint list is a retrieve data connection. At the Data Connection under the Data tab , create a data connection which retrieves data from a SharePoint List. The wizard will then prompt you to provide the SharePoint site, and from there, select the SharePoint List or Library from the list. You will also be prompted to select for columns which to wish to display. Provide the other necessary details and exit the wizard.
As for submitting, there's a blog here and an active discussion thread right here. For a codeless, approach, you may want to try out qRules' SubmitToSharePointList command. It's pretty easy to use and require less work.
Hope this helps.