Graphic/Image/Photo size

I would like to be able to "resize" my graphic/image/photo but have not been able to do do.

When I click on the button for adding an image I get the two img brackets with a url between them.  I edit the url so that this is how the journal page looks:

The problem is that the image is too large for the monitor and I have to scroll down.  I would like to make the image 25% of the original size and have tried both width and height coding, but then the image does not appear.

Does anyone know how to "resize" the image without having to physically resize it?

Please respond to if you have a solution.

Thanks, Phil