Hi,
Dear Sir,
I am glad to inform you that I'll plan to go for Tirupathi on 2nd July, 2009.
Hence please grant me 2 days leave i.e 3rd July, 2009 and 6th July, 2009.
Thanks & Regards,
The above is probably fine in the Indian style of English.
Here's how I'd write it in Canada. As you can see, it's more informal, and we usually don't explain the reason.
Dear Tom,
I would like to take two days of my vacation, on 3rd July and 6th July.
Thanks,
Clive