IRFANVIEW is a great free image resizing tool. www.irfanview.com
Here are fast detailed instructions on resizing images to get them less than 100K
Open image in irfanview
by going to File - Open... and locating the image on your computer
go to Image - Resize/Resample...
Where it ways Width (under Set new size) if your image is GREATER than 600 pixels then enter 500 or 600 pixels in that box then click OK. If your image is smaller than 600 pixels, just click OK. NOTE: By changing the Width, the height will and MUST also change as well.
Make SURE that the Preserve aspect ratio box is checked. Make SURE the Size method: is set to Resample (better quality)
I`m attaching a screenshot below. I used it to resize a photo that was 800x1200 pixels and was 281 KB
go to File - Save as... choose JPG-JPG/JPEG Format where it says Save as type from the dropdown menu. The default setting there should be fine. Just make sure the slider is set at about 50.
Doing this should get you a file that is less than 100K
If by chance it isn't, then just go back and move the slider to 40 when you are saving.
That should work and give you a photo that is the right size and NOT fuzzy.
Hope that helps,