If you are unable to adjust the resolution on your camera, any photo type software can reset the size of your photos. I use an old version of Jasc Paint Shop to accomplish this. My ideal width on this site is 650 pixels. If you look at my HSc "sticky" on Instruction Manuals, note the width and you can see how this fits the screen.
There is also a limitation of four on the number of attachments allowed per post. If more photos are to be posted simply start a new post with each batch of four. Again, you can see on the "sticky" how I handled this.
Hope that helps you.