Now, for us dummies, could you tell us what is the best size for posting them and how, when, and where to do so?
VCA Members get 500 MB of space in the gallery. That's alot, but with hi-res cameras being so readily available these days it can go fast! I would recommend photos be sized no larger than 1024x768. Any larger than that and they probably won't fit inside most people's browser windows without having to scroll vertically or horizontally to see it (unless they have a ridiculously high resolution on their monitor). For general stuff that you want in a post here on the forums, 640x480 or similar is good (maybe slightly different depending on your camera's aspect ratio). This way the photo fits comfortably within your post, it's big enough to retain detail, etc. But if you're uploading something that's wallpaper/screen-saver worthy, the bigger the better (this can eat up space fast though, as some of these can be upwards of 3Mb per photo in size).
How: read through this thread, then visit the gallery and experiment a little. You won't break anything!
When: Whenever you have a photo pertinent to a topic being discussed, or if you just want to share your latest shutterbug creation...that's entirely up to you!
Where: Again, the gallery is a great place to store photos. There are great options out on the internet for free image hosting, I believe some of them are mentioned in this thread.
Happy picture posting!