Appending the text

Hi all,
I have a written code to save the data with respect to the text entered in the previous value . Suppose if i given the text as 2 it will show a form if i enter some values and click on save that data should be saved in some text file and the same form will be shown with clearing the values. If i enter some values and hit save again the values should be append in a new line in the same text file...

Ex : if i enter some values as 1 XYZ ABC for the first time these will be added

2nd time i will give value as 2 DGH FGH this should be appended in the same text file and the text file should be like

1 XYZ ABC
2 DGH FGH

Any help