To log this cache as a find you must fulfil the following conditions
1. Sign the log.
2. Have found at least 5 caches with the Field Puzzle attribute.
3. Have found at least 5 caches with the Special Tools attribute.
You can check that you qualify by looking on your Project Geocaching profile, I can also look here to verify your qualification. If you choose to hide your profile you can either list your qualifying caches or post a screen shot of the relevant part of your profile page.
You may sign the log at any time posting a note to the cache page, but please don't post a Found It log until you qualify.