Where is he i already download dawn guard i went to the ragged flagon and he's not there and also guards are not telling me anything about dawnguard please help ...

You need to be at least Lv 10 for the guards to chat about Dawnguard, if you aren't.
Other than that the Character Makeover Lady ([censored]) is in the Ragged Flagon, she'll be sitting down on the wooden platform over the big pool, to the right.

Also when you can, go to a Forge and see if you can make Dragonbone Weapons. If not then your DLC may not have downloaded correctly, just check that out.

oh i think the DLC didn't load it fixed now thanks

No problem and enjoy!