When you are creating a contact form you will have the option in each of your form fields, to display data entered into that field on the contact's side bar.
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To do this, navigate to the contact form you are interested in by clicking on Forms, then the Contact tab, then the Customize link next to the contact type.  

Toggle open the settings for the field you'd like to show, then select Visible on sidebar.  

Save your changes.
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Now you should see that information on the sidebar for all contact's with the contact type you selected data from!
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Important to note!  Only contact forms will reveal data on the sidebar. You will not be able to select data from a regular activity or assessment form to show on the sidebar.