All messages are stored in text files with the .SIL extension. When you want to modify or translate texts, you open the .SIL file you want (for instance, English.sil) in Notepad++ or any text editor.
Then, in XLS Padlock, go to the “Localization” option and enter the path to the .SIL file you modified. Thus, XLS Padlock will use your modified texts.
Ignore that option, it is used in some specific cases.