Majority of ETFs (Exchange Traded Funds) are index funds that were designed to replicate the performance of a stock market indexes. The QQQQ, SPY, DIA, IWM, XLF are the most popular index tracking ETFs. Index fund (commonly called stocks ETF) seek to track the performance of an index by holding in its portfolio stocks from the basket of the index. There are several types of index (stocks) ETFs. Among them you may find leveraged ETFs which are constructed to to seek a return that corresponds to a multiple (as a rule double) of the daily index performance and short ETFs which are designed to seek a return that correspond to the inverse (opposite) of the daily performance of the index.
Naked options trading is very risky - many people lose money trading them. It is recommended contacting your broker or investment professional to find out about trading risk and margin requirements before getting involved into trading uncovered options.