Interactive Frame Designer

When you create "frames", you can tailor the built-in frame templates to meet your exact needs. Once you have selected the template which is the closest match to your desired layout, clicking the template icon, will open the interactive frame designer:

Use you mouse to "drag" the black lines of the frames around to resize them. Additionally, you can also manually enter frame sizes in the boxes below the area where you can resize frames with your mouse. Click "OK" when you are happy with your new frame sizes