Mike,
there are two situations where this sort of thing happens:
- when posting from a Phone or tablet, a photo taken on said device. The Phone and tablet know the orientation, saves this in the EXIF data, and will show you the photo correctly. It will be uploaded the way it was stored however.
- when posting from a PC, if the photo was taken on a camera with orientation detection, it is also saved in the EXIF data. Some (but not all) software packages will autorotate the photo upon display. Uploading the same photo will then leave it in the wrong orientation. Check how the photo displays in the file manager... if incorrect, you'll need to rotate it before uploading
Check your post after uploading. If it's incorrect, Modify your post, delete the incorrect attachment, rotate the photo on your tablet or Phone or PC, save it and then attach it again.
You can use tools like Picasa, Irfanview, or XnView to do this...
Note that even though our software resizes images, it does not compress them a great deal. If you resize and compress an image before uploading, you are helping greatly!
Peter