As for posting them, you can do one of two things.
1. Go up to Pictures to go to the PhotoPlog. Click on upload, browse to find the picture you're wanting to upload, click on it, press ok, then click on upload.
2. If it's in a thread, it definitely has to be resized. You click on Post Reply. Type in your message, scroll down to manage attachments, then basically follow the same steps as #1.
This is from memory, so I apologize if it's not totally accurate.