how do I change the amount/size of the persona shown

Add extra empty toolbars if you want to see more of the persona.

You can create new toolbars in View > Toolbars > Customize

You have to place something on a toolbar (drag a Space on it) before closing the Customize window as empty toolbars are automatically removed.

See http://kb.mozillazine.org/Toolbar_customization

i really cannot figure out how to see more of the picture in the browser.

1. Go to View > Toolbars > Customize
2. Click the "Add New Toolbar" button to create a new toolbar
3. Give that toolbar a name like persona_1.
4. Drag a Space item with the left mouse button pressed on that new toolbar because empty toolbar are removed automatically if you close the Customize window.

Repeat steps 2 to 4 if you need more vertical space. Adjust the name to persona_2 , persona_3 etc for those extra toolbars.