Newbie Equipment

Swim - Goggles, Swim Cap (if you want) - and a place to swim...

Bike - Do you have a bike? You will need some kind of bike to ride. Helmet. Cycling Shoes (only if you are clipping in). Bike Tools

Biking requires the most equipment. If you do not have any cycling experience or a bike then you will ned to set yourself a budget and then work from there. Many people start their first triathlons with a mountain bike or hybrid.

Run - running shoes

You didn't provide much info on what experience you have or what your goals are; what is your ability level to date what type of distance are you planning on doing, do you want to just finish or be competitive...... You can get away pretty cheap on the swim and run. Tri shorts or a trisuit is recommended. You can use your tri shorts to train in on your bike or you can get some cycling shorts.

I ran track in 7th grade and i did pretty well in the 800 m. Finishing 6th out of 15 in the county. I have a walmart mountain bike right now. Rite now my goal is to not finish last.

She's right about the equipment.  Great goal; it's my goal too.  Good luck!

I'll assume you want to do a sprint triathlon (600 yard swim, 12 mile bike, 3 mile run for example)

Good running shoes
(They should be replaced every 300-500 miles if you don't outgrow them)

Swimsuit
(Any type works. Form fitting for less drag in the water if you want.)

Bicycle in good working order
(If you have a mountain bike, ride it. You won't be alone.)

Bike Helmet
(Most races won't let you ride without one, and even if they do, why would you not want to protect that very delicate and irreplacable part of your body.)

This is probably all that is REQUIRED to complete a sprint-tri. You might be required to wear a shirt (any old T-shirt will do).

A few more things are highly recommended.
Goggles for the swim.
Water bottle for the bike.
Tool kit and patch kit for the bike.
Bicycle pump
A dry-wick shirt instead of a cotton T.
Sun protection (sunscreen, hat, sunglasses)

The list of things you just WANT gets really long...
skinsuit
tri-shorts & top or tri-suit
bike shoes & clipless pedals
faster bike
energy gels
faster fancy bike
transition bag
really cool, even faster, fancy aero-bike
Heart-rate-monitor
upgraded wheels to go with the really cool, even faster, fancy aero-bike...