Where can one find a list of penny stocks?

Investing in penny stocks works just the same as investing in any other stock. You buy the stock using its symbol

Example: XYZ is the symbol for Xray Yellow Zoo Inc. (company is not real)

You open up an account with a broker that does not penalize you for investing in microcap or penny stocks, place a "limit buy" order for that symbol and determine the number of shares you wish to buy. When the time is right to sell, you place a "limit sell" order indicating the number of shares you wish to sell.

Remember, penny stocks are highly volatile, meaning that their price can move up or down by leaps and bounds in a short period of time, this is not the case with all penny stocks, just the ones that are worth your investment.