Highlight whatever you want to paste, press ctrl+c (Copy) and then after you want to copy the thing you want to put into minecraft, go to chat and do ctrl+v ; However, you cannot copy the color code symbol into minecraft. The color code symbol:§
The Meaning of Life, the Universe, and Everything.
I had a little trouble with this too, to copy and paste in Minecraft you use Ctrl+A to highlight the text in chat and use Ctrl+C to copy it and Ctrl+V to paste, if it's outside Minecraft, you just use Ctrl+C to copy it then use Ctrl+V while in Minecraft to paste it. Hope it helped