Just paste your code into Code field, and hit SEND button.
If language autodetect will fail (and sometimes it will), you can always edit your last entry!
Your code snippet will be deleted after 7 days, but if you check Hold it will be deleted only if nobody look at it for 30 days.
And remember - have fun! :)
Also you can use our vim plugin (usage: :Paste - creates paste from the current buffer or selection).
Thanks to Rafał you can now use command line tool (read source for usage).