Run the Tab Setting applet on the Settings Home page.

With an item in the lefthand column selected, click on the document icon to create a new tab and give it a name, such as Office. Click on the icon to change it.

You can change the position of this tab relative to the other tabs by tapping on the up and down arrow icons.

If you want to create a new application link in this tab then with the application column in focus (indicated by a dotted line around the column heading - tab key will switch the column focus), tap on the new document icon. Give the application link a name, tab on the icon to select a new icon and tap on the '...' button to select the application.

If you want to move an icon from an existing tab then select the application in the orginal tab and then tap on the arrow pointing left. You will then be presented with the list of tabs from which to select.