Wayne,
To resize a photo, first, double click on it on your computer to open it in a viewer program. Now right-click on it, then select "Properties". The popup window will tell you how large in KB the photo is. You will need to resize it to 100KB or less.
Now close the pop-up window and double click on the photo again. A window will probably pop up asking you what program you want to open it with. Select Microsoft Photo Editor (which comes with any Windows computer). The photo will then open in a photo editor window. In the upper left side, you will see several options above the tool bar. Select "Image" and scroll down until you see the "Resize" option and select it. A window will open which allows you to resize the photo by selecting width and height in inches, or simply by size percentage. The percentage is easiest. Just click the arrow down until you get to the size you want (If your original photo was 250 KB, then you know you need to reduce it to about 40%, since 100/250=.4). Then click "OK".
NOW THIS IS IMPORTANT: No changes have been made to your original photo until you click "Save". If you want to keep the original as-is, you must go back up to the "File" option and scroll down to "Save as". Click "Save as" and a new window will open, which allows you to save the smaller photo under a new name. Rename the photo. This will allow you to save the new size photo without changing the old one and keep both. If you screw up and just click "Save" your original photo will be changed and there is no way to change it back. If you resize the small one back up to original size, it will be fuzzy and low resolution.
This forum restricts the size of uploads to 100kb per item. After you have saved and closed the photo editor, you can right-click on the photo, then select "properties". The pop-up window will tell you the new size in KB of the photo. If it is larger than 100 KB, it is still too large.
Hope that helps!