if you go to the links above to the one called "my account" then when it loads up, look down the left side for "edit signatures".
enter what you want to show every time as a link. to do so, you open brackes ([) type url=, the enter by typing or copy/paste the address of the post. What I do is click on the post number from the upper right corner of the post of where your character is and it will give a view of a single post. copy paste to the spot after "=" , the close brackets, enter the character's name and the open brackes again and type "/url and close brackets.
if you want it in a spoiler block (sblock) so the same with sblock with the bracts above and then /sblock below. make sure all commands are encased in "[ ]".
i think that is what you are looking for.
edit; i took a look at his sig and i realized I forgot a step. When entering the first sblock, enter as: sblock= (enter subject such as character name here) then close brackets.
Edit: I almost forgot. scroll down the page until you find the "save signature" button