I want to transfer a digital copy of the thing2 onto my iPad I've got the digital copy on my pc but how do I transfer it to my iPad ? Thanks in advance !

On your computer open up iTunes and then on the top left blade click "File" and then "Add File to Library". You can then browse to the digital copy of your movie to add it to your iTunes account. Plug your iPad into your PC and then click on your iPad under "Devices" in iTunes (left hand column about half way down the screen). Now click on the "Movie" blade that is close to the top middle of the iTunes screen (below the Apple symbol) and there you can check the "Sync Movies" so that the digital copy of your movie is sync'd to your iPad. Hope this helps.

can ipad play all kinds of digital copies? i have a digital copy file with .wmv format, iPad supports .mov, .mp4, .m4v, im confused about this, any thoughts?

No, only formats supported by quicktime.

also if the movie has any type of DRM that is not from apple, it won't work without you converting it to some other DRM free format.