send a postcard to Post Secret

Well, i know which secret i’m going to use.
so now all i have to do is create a postcard,
and have the guts to send it.
(Does anyone have details about what the postcard should be on, like…can you buy blank postcards? or do you have to cut them out of manilla tag…if you cut them out, what do you have to write on them..and how many stamps? sorry about so many questions, just i’ve never really mailed a postcard before, only letters. And i wouldnt want to ask a postal workere, because i dont want them to know the secret, you know? so if anyone can help, it would be gratly appreciated =] )

i read post-secret every sunday.
and every time i feel bad about myself.
they can really make my day.
i want to send a secret so badly.
i would love to make someones day with my secret, like so many have made mine.
=]