1. You should register on www.flickr.com, to get an account.
2. Have Firefox and Install PFF 1.3
3. install oakflickr4pff
4. from PFF1.3 "setting" to enable oakflickr4pff addon, and restart firefox
5. try to write a blog with PFF, paste some local picture files or picture from clipboard, and try publish it.
6. the authentication page will be activated. you first log in to flickr, second allow "oakblog" to access your flickr, it is the application name I used for oakflickr4pff in past. If success, click the button on oakflickr panel.
7. try to publish the blog again, it should works.
8. you don't care the photo upload from now on, oakflickr will check/upload it automatically, while you are publishing the blog.
refer to http://gsm.chenzhiyuan.googlepages.com/oakflickr-guideline.html
for step by step guide.