The simple way is to use string table.Go to resource view -> string table and add a string with ID same as your icon(same as menu id) and give the text like tesxt1\ntext2
For example for save menu string will be,
ID_FILE_SAVE 57603 Save the active document\nSave(Ctrl+s)
"Save the active document", this text will be displayed in status bar if place the cursor on save menu item and "Save(Ctrl+s)" will be your icon tooltip(comment in your way)
One more method is go to menu editor open its properties and give the above(Save the active document\nSave(Ctrl+s)) text in
prompt
field.