The text box control is build off of the standard Microsoft .Net control.  The properties for the standard control can be found here http://msdn.microsoft.com/en-us/library/system.windows.controls.textbox.aspx. 

The added properties for the control are ACTField, ACTSecurity and EntityName. 

ACTField is the field that the control will save to
ACTSecurity is the field where the control can be made non editable based on users or teams.  To learn more about adding security to controls go here Add Field Security .
EntityName is the name of the table that the ACTField is coming form

See also