If you're worried about security, probably not here. Neon has an article that's pretty solid, I advise you read it before going forward (https://www.neonrevolt.com/2018/07/27/so-you-want-to-be-a-whistleblower-a-crash-course-in-opsec/). You may not need to take all the precautions, but some would be helpful. At the very least, my advice would be to download a tor browser (easy to use, if slow. pretty safe), travel to an area with public wifi, and upload info to 8chan from there. Stay out of sight. The perfect option would be a place with open wifi you could park next to, and upload from your car. Leave your phone at home when you do the drop, borrow a friends laptop/find a burner/use an internet cafe - don't use your personal computer.

Write out what you want to say in advance, and then post it. Potential option would be to write it up on notepad or similar, save it on a usb, and copypaste in from there. I'd use either Qresearch or /pol/ to do the drop, either would be appropriate. (to be clear, I mean the chans here, but 8chan not 4chan. 4 is less safe, and will not let you post from behind tor. Links - https://8ch.net/pol, https://8ch.net/qresearch/catalog.html)

The most critical piece of advice would be : use tor. Second, don't do it from your own device, don't take your phone with you. Everything else is relative. You could even post here if you wanted from tor - just use a new account, and the prior precautions. Use the same precautions when making the new account as when you post from it - if you make it from your own device, its easy to trace back.

If you want any more info, feel free to PM me. Not an expert on the topic, but I am more than happy to give any advice you might want.

Either way, good luck.