Just your mouse pointer on an empty spot on the taskbar, left click and drag it in an arc to the bottom of the screen and release it.
You can also check START--Settings--Taskbar and autohide it for a bit more screen space (you have to move the mouse "beyond" the bottom of the screen for the taskbar to appear then).
[This message has been edited by Narada (edited 10 January 2000).]