In photoshop, or other photo editing software I:
- convert file format to JPG
- shrink the picture to 640 pixels, or less
- save and compress file size to about 200K
I then upload the file to an image hosting site - Photobucket, Use, etc. My preference is Use.com, but they all work. Go the option to generate code for copying to forums and select the appropriate code, which is then pasted into your profile or body of the message. Ensure it has IMG in square brackets before and after the string of code.
I normally find I have to tweak the code for it to work properly.