To save a form's data you'll need to add the Database Save Action to your form.
Once data has been saved, by default its data will not be accessible in the Form Data Browser. Access to form data is assigned to users by editing their iCM Privileges. You can also grant access to a form's saved data one form at a time, while designing your form.
Right-click on a form and select "Secure this form's data". You'll be taken to a screen that lets you choose the iCM Groups/Users who are allowed access the form's saved data.
Use the "Select" button to add users. Highlight a user and click "Remove" to remove them.
Take care when deciding which forms should be made available to the Form Data Browser. Also note that any actions (email, workflow, and so on) that are present on a form will be triggered whenever that form is used to edit data within the Form Data Browser. See Form Data Overview for a full discussion.
It is worth noting that securing a form's data in this way controls whether or not this form is available in the Form Data Browser to view data with, rather than securing the data itself. In theory, if your form used an external type definition, you could use one form to view the saved data of another.