Ok if you download irfanview, open your file in irfanview.
Go to Image - Resize/Resample - all I did was put the width at 500 pixels and clicked ok.
Then I went to File - Save as..... and chose JPG - - JPEG for their dropdown menu.
Once I did that a new window opened where there is a slider to choose higher or lower images.
Like I said - Personally I always use 40 or less
Then just save it.
This was just a quick way that I was able to do it in Irfanview, I'm sure there are equally good or better ways to do it in Irfanview or other graphics programs. Irfanview is a really easy program to play around with.
If others have input please post in this thread - we will make or add this to a posting sticky.