Bruce: There are size limitations to each image (200 kb), and to the total images in a single post (500 kb), so generally one has to use some software to reduce the *file size* (Note, the limitation is on the FILE size, not the actual image size). Several ways to reduce the file size of a digital image:
1) Use of JPEG- of course most images we deal with today are already Jpeg, but you should check this.. Generally converting to JPEG will reduce the typical file size by a factor or 3-4 without visible loss of image quality or size.
2) Reduction of the size of the image (ie. from 3000x4000, to something more appropriate to a screen.. maybe 800x1000 or so?). I think even PAINT will do this... and of course any decent image proc software will allow all of this.
3) Use of a file size reducer (I like 'Light Image Resizer' which you can download from here )-
http://download.cnet.com/Light-Image-Resizer/3000-12511_4-10529104.html Light Image Resizer works on already JPEG'ed file, by selecting more optimum JPEG factors to gain further reduction. The user gets to specify 'how much' reduction they desire. Just compare the file size before and after use a few times to determine how much reduction you need.
Light Image Resizer works great and is what I use.
(Edited as requested to fix minor typo)