Please help with links

I know this is the second post for today, but just a quick one, if anybody can help me out there in blogland. Something very simple, but I can`t seem to get the hand of linking my cards to challenges in the comment boxes if there is no Mr Linky. I`ve used the code that some people put on their blogs, but when I put it in the comments box all the code comes up and there`s no link. I know it`s something very simple, but just can`t get the hand of it. Hugs Val xxx