You should use caution and study hard and long before you invest. Commodities accounts involved substantial risk, particularly for inexperienced speculators. Do not believe that "it's easy to make a killing" in commodities, or that any one person "has the secrets".
If you are sure you want to, you may open an individual account with a registered Futures Commission Merchant or through an Introducing Broker. An Introducing Broker may accept your orders and transmit them for execution to a Futures Commission Merchant with whom she or he has a relationship. An Introducing Broker is not permitted, however, to accept any funds from you. All funds are deposited directly with a Futures Commission Merchant.
You may also trade futures and options on futures by participating in a "commodity pool." In a commodity pool, you are purchasing shares or interests in the pool, and trades are executed for the pool as a whole, rather than for the individuals who participate in the pool. Pool participants share ratably in gains or losses.