To 'copy' the image you will need to press the 'Ctrl+C' button on your keyboard to copy your computer screen. (Or just right click, and copy image) To 'paste' you will need to press 'Ctrl+V' on your keyboard to paste. You also need 'Paint' open for this to paste after you've copied it. After you've done all that, you need to go to 'Imageshack.us' to upload your pictures. To upload your pictures from Imageshack, click on the 'Browse' button and select the pictures that you are wanting to be uploaded.
After you've selected your pictures that you wanted to be uploaded and ready to post on forums or anything else, click the 'Direct Link' on the right of the browser.
After that, right click on the 'Direct Link' and click 'Select All' (to make things alot faster) and then punch in 'Ctrl+C' (to copy).
And now after that, go to the forums page that you're posting in and there are many links to put your link in. Click on the link that's for 'Images'.
Hit "ok" and copy the URL that is created.
Then there you have it! You've just learned how to copy screen, copy & paste all at once. (If you didn't already know how to do all this) But if you already know how to do this, that's good also but if you don't, then there you have it right here on these forums. I hope this guide helped you learn how to copy screen, and copy & paste.