You either need to resize the photo to 650x550 so you can attach it directly to a post or use a service like photobucket.com to upload your photo and add a link to your post.
I use photobucket....It's free and very simple to use. Upload your photos to your photobucket account, then copy/paste the link into the body of your post here.
What I did to cut down on the memory size of the photo, is open your photo with the paint program. Then resize it to a size that will require less memory, until you find a desired level.
