Look at the top of your current press, does it have what looks like a hex nut. Just unscrew the nut. If the dies won'rt fit the hole you can get an adapter from CH4d

You will find it listed under presses-Press Top Bushing

If no nut you need a different press.

Get yourself an RCBS Rock Chucker Supreme from Midway for $96. Rockchucker Supreme

That Lee Classic press is not very durabale. The Lever Knuckles keep failing and the ball knob keeps falling of the handle.