Attention: This import is for the old bitcoin24.de site which was closed in April 2013 (not to be confused with bitcoin-24.com). If you still got your JSON export code from bitcoin24.de, you're lucky and you can import all your trades.
If not, visit http://kuttler.eu/post/what-happened-bitcoin24/
where you can find a link to the old server and try to login into your bitcoin24.de account.
1. Go to http://bitcoin24.de/ and login into your account
2. Click on the left side on Transactions and then on the top on Json Export (see screenshot)
3. Copy the complete code (Ctrl + A, Ctrl + C), it's only one big line of code
4. Paste it to the box below (please make no changes) and click the button
>>> [Show/Hide the how-to screenshots] <<<