As mentioned by Gopi in previous reply. Bind the UI element group Visiblity property to a context attribute of type BOOLEAN and set the context attribute Accordingly on button click event. You can also set the default value to context attribute if you want to set that invisible first time.
You can get the text entered by the user on text edit by reading the context attribute which you have bind to the UI.
1) Every group has an attribute Visible, so bind a value to it (GRP_VIS TYPE WDY_BOOLEAN)
upon clicking the button pass GRP_VIS = 'X' which means its visible
Use an another button to hide it by passing GRP_VIS = '' which means its invisible.
2) bind a value of type STRING to it and u can get the data of the text edit into the string.