How to save the GUID of entered item in textbox?

Question

hi,
if i enter data into textbox,click ok button then that items GUID is saved in table,i want save the GUID of which item i entered in to textbox.i dont want save the entered item.i know the codeing of combobox for this same task,but i don't know in textbox.plz give the code,plz help me,plz