I only have Photoshop so this is all I know. If you have a different version then CS5, your menu may not be exactly where I have explained but they are all there, not far away.
First you will want to open your picture, then on the bar at the top of the photo right-click on it and you will select > Image size
Then you should see this box pop up….
The first thing you will want to do is change the resolution to 72 pixels/inch, then you can put int height, if you have constrain proportions checked it will do the rest.
You may have to click on this next image to see better but the only thing you really need to do here is to click on the drop down where it says Quality and there will be a slider. As you move that slider back and forth look in the lower left of the picture it says JPEG and it will change the size as you move the slider. You will want this to be at about 50%. This will give you a decent size picture for the web and it will not be great quality if someone takes it off the web and tries to print it. It won’t be completely distorted but you want your web images to be decent quality. If you have the option to convert to sRGB, that is great check it. I am not sure if Elements does or not. I am sure Elements works in sRGB anyway.
When you click on SAVE, Save it to your folder that you have created for the web and you can always know everything in that folder is downsized and web ready.
I hope this has helped. It is the perfect way to post your crafty pics to your blog! If you have any questions please feel free to ask!
Since I have made this tutorial I have changed the way I resize for the web, you may want to check it out here!