HOw to play Farcry HDR+AA

If any patch allows HDR/AA (which is uncommon for games, but possible), it will be the latest patch, or will be included in the latest. Go to the official website for the game to download the latest patch and install it.
You should also check out the software that came with your graphics card. I don't know about ATI, but nVidia's included software has options such as AA/Texture filtering that can be enabled for any game or application (I use this for all games that don't have the settings). What gave you the idea that a patch will add HDR? Are these options included in the game, but not working?

To find the official website, look on the box and go to the game company's website. They will have the newest patch for the game. You just run the patch by double-clicking it and it will give you some (Next> buttons to click.