Do you have some WMV(Windows Media Video) files on computer and want to import WMV to iTunes then watch them on iPod/iPhone/iPad? here is a detailed guide around this issue:
The tool we will need:
A WMV to iTunes Converter – Video Converter Ultimate (Windows 7 Compatible)
Video Converter Ultimate is a nice WMV to iTunes Converter software which supports converting WMV to iTunes compatible format MP4 and other files like MOV, MPEG, FLV, MKV, AVI, M2TS, MTS, MP3, etc in one click with powerful editing functions.
Free Download Video Converter Ultimate, install and run it, then click "Add Files" in menu list to load WMV Movie files from your computer to the main process window of the software.

iTunes plays files that are in mp4 format, so just Select "MPEG-4 Movie (*.mp4)" under Common Video as output formats in "Profile" drop-down list. the default settings is recommended to use for newbie, advanced users also can customize output video audio parameters like bit rate, resolution, etc.
You can click"Browse" to specify the output directory to save the converted files.

Note: Video Converter provides smart video editing functions like Cropping (cut off the black edge of movie), Clipping (trim your favorite segment of video to convert), etc, you can edit your WMV video files before WMV to iTunes Conversion.
The last step is to click "Start" button, then the Video format Converter will automatically convert WMV to iTunes MP4. The conversion speed mainly depends on your original video length.
Now you can feel free to put converted WMV Movie files to iTunes and sync them to play on Apple Devices iPod/iPhone/iPad.
For DRM WMV WMA files downloaded from Amazon Video on Deman, Napster, Windows Media Player, etc, you can go to this tutorial for the details to Convert DRM WMA WMV to iTunes for iPod iPhone iPad.