You can resize an image by adding width and height commands to your HTML image tag.
The image we'll be resizing is below. First, we'll need to know the current height and width of our image. Right-click on the image immediately below and click on Properties and you'll see the image dimensions listed in pixels. This image is 333 pixels wide and 223 pixels high, lets make it one third larger.

This is the tag before we add new attributes to it

<IMG SRC="http://yourimagehost.com/yourname/yourpicsname">

And this is how it looks when when we make it one third larger

<IMG SRC="http://yourimagehost.com/yourname/yourpicsname" WIDTH="444" HEIGHT="297">

To make it half its size, we'll just halve the dimensions like this

<IMG SRC="http://yourimagehost.com/yourname/yourpicsname" WIDTH="166.5" HEIGHT="111.5">