HOW DO I ADD A LINK TO MY ANSWERS( OR QUESTIONS) IN Y!Q&A?

I CANT SEEM TO ADD A LINK TO OTHER SITES eg YOUTUBE. I KNOW I'M COMPUTER ILLITERATE! I'VE TRIED COPY AND PASTE BUT WHEN I COME BACK TO Q&A THE PASTE OPTION ISN'T THERE. I HOPE YOU KNOW WHAT I'M TALKING ABOUT!