@vikram1, a similar question has already been asked (by you) and answered (by me) in another thread:
As @Tut wrote above, you don’t need a custom template to do this. You can do it with HTML in the notes field of your invoice. There are many examples in this forum – including in the thread cited above – to get you started. I’m guessing that you’ll need help from a local resource who is familiar with HTML.