There's no option for antistropic filtering in the in-game options :/
Unless you mean my graphics card, in which case I have no idea how (I use an nvidia card btw).
You should have an icon on your desktop 'Nvidia control panel', or it will be in your programs list in your start menu, click on it to bring it up, then look in the menu along the left side for 'manage 3D settings'. Select that, and it should take you to a screen with two options along the top row, the first is 'global', which is the overall setting for your rig, and the other option is program specific...you can actually set a different graphics setting for each of your individual games. In either of those menus, you can turn down your anisotropic setting by lowering the number. You can also change your entire graphics setup to suit yourself...
The other option you have is to click play in your steam game listing (for skyrim) and when the small menu pops up with 'play', 'options', 'data' etc, select options, and you can then set your anti-aliasing and anisotropic settings in that. If you prefer, you can set your global settings in the Nvidia control panel to let you select those settings in game through that skyrim menu.
If you have any issues, pm me. Good luck.