Typically, you cannot shape or apply a gradient fill to a text block. If you plan to do this, it becomes necessary to first break apart the block to create individual shapes that can be modified with the various shape tools. In Flash 5, this is accomplished by selecting the text block with the Arrow tool and then breaking it into its component pieces via the aptly-named Modify -> Break Apart command.
Once the individual components of the block have been separated, you can use the drawing and colour tools to apply different kinds of effects to the object. Breaking apart a text block is a necessary precursor to applying a shape tween to the object.