First you need to capture the screen.
Briefly hold down the "power" button at the top of the iPad, then press the "home" button at the bottom of the iPad which still holding the Power button. Don't hold the "power" button for too long or it will switch off the iPAD. you will know that the screen has been captured because you will hear a sound like a picture being taken on a digital camera.
Email it from your PC
The picture will be available in "photos", if you have this setup to Synchronise with your PC in iTunes then you will be able to email it from your PC after a synch, normally it will be on your PC in your "my pictures" folder.
or Email it from your iPAD
If you want to email it from your iPAD then Click the "Photos" application in your application dock at the bottom of the screen (Sunflower). Then Scroll to the screen you captured, it will be at the bottom. Then click the thumbnail, it will open in a preview window. Finally in the top right hand corner, second from the right click the arrow icon, this will provide you with the option to send the screen via email.