How do you make a cure for vampire bite in sims 2 for PSP?

First, buy a work bench (what you use to build Mechanical skill).

Second, buy Plasma and Garlic seeds at a store (Mambo Loa's store, for instance).

Third, build your Cooking skill until you have 4 Cooking. This can be done by cooking or reading about cooking.

Fourth, go to your work bench and press Create.../Vampire Potion.

When you've made the vampire potion, then you can drink it by pressing the Right and Left buttons until it appears. Then, press the x button.