Read about it here —
The instrument you can use is the U.S. Gasoline Fund (UGA), which is an exchange-traded fund (ETF) that tracks the price of gasoline futures.
You can purchase any ETF just like you buy a stock. Do this in your regular borkerage trading account. You can even do this in a self-directed IRA or Roth IRA, and some of the better 401(k)s out there that actually let you buy individual stocks. You can also set stop orders on ETFs, to minimize investment risk (just like a stock).
An ETF is the same as a mutual fund, but without all the fees and expenses. Plus, like I said, you can minimize risk with an ETF (unlike with a mutual fund) in that you can set a stop order so that you don't lose more than X% value if it drops in value.
Airlines use similar investment strategies to hedge against the price of gas. Read the article link for details.