Ya open your pictures. shrink the page in half. open paint from your computer shrink in in have you'll have two pages open. drag your picture to paint and drop it there. It will be huge you won't even see your object. Close your pictures. open paint up full page. Now up on the top bar of paint, it will read image open it and find skew keep reducing by 50% both at ones till its about a 5x5 left corner of you screen click off it will ask you to save it say yes. go back to you pictures and right click that picture and select properties it will now tell you the new size.
open with your desktop picture button.... double click any photo that you would like to resize ....go to bottom right, and drag the size bar to desired size....save and post.
Alternatively, drag photo into or open with in PowerPoint. Right click photo in PowerPoint. Choose "size and position". Select desired Height in inches. Hit enter. Right click image again. Select "save as picture". Select save as jpeg. Save to desired location (desktop etc..). Done.
Two suggestions,
One, set you camera for the lowest file size which is 640 X 480, plenty good enough for 99% of your pictures (save computer space too) Then you won't have to do any resizing at all. More people should be doing this.
I hate oversized pictures. on forums, and in emails.
Another good program which is free and easy to use is, VCO image resizer. just select your picture, set width to 640, that's it. It creates copies by default, (but can also replace) in case you ever want an enlargement of the original.