As you will also see, you can designate your image as an Image Map & give it the URL of the Client side image map. Once you click on 'Select Picture', you can browse to anwhere your image is, select it and it will appear in the box in the lower portion of the dialogue box. The width & the height have been entered for you, so there will be no calculation necessary, unless you want to change the sizes. If you do not enter a number in the Border text box, then the default, Border=0 will be used.
Once all the data is exactly how you want it, just click the 'Apply button & the information will be transferred to your web page.