How do you have a lurker on starcraft

You need a Hydralisk first of all.

Secondly, you need a hydralisk den.
You also need 50 minerals and 100 gas.

And of course you need Starcraft: Broodwar

When you have that, select your hydralisk(s) and to the right of the menu button, there will be a button and if you press it, the hydralisk(s) will turn into an egg and then (a) lurker(s).