-- To upload
id = http.post("http://immibis.com/ccpaste", data).readAll() -- id could be "E:" followed by an error message

-- To download
data = http.get("http://immibis.com/ccpaste/"..id).readAll()

Demo program, works like pastebin

Edit: Thanks AfterLifeLochie for moving this to the right forum.

Edit 2: tiin57 made a hastebin program, you might as well just use that.