How to use Hawaiian Tropic Tanning Lotion?

I have a bottle of Hawaiian Tropic Tanning Lotion Sunscreen, SPF 4. I have medium-toned skin - not pale, but not tan either, and I'm planning to lay out in the sun tomorrow. Does this stuff help with the production of melanin, or what? And how often should I reapply it? Any other tips, recommendations are appreciated.