If you don't know where to start investing, start with an Index Fund that tracks the S&P 500 such as $VOO.
You could have over $1.3 Million when you are 60 if you invest $100 a week into an S&P 500 index fund, if you start at 25.
The S&P 500 is a group of America's largest companies, which have returned ~11% per year, on average, from 1928 through 2023 with dividends reinvested.