[downvoteme1]

For starters, open a brokerage account at a broker that provides an API. There are many currently available including Ally, Tradier, Alpaca, Think or Swim, Interactive Brokers etc. Although, I think Think or Swim is currently not providing new keys due to their merger with Schwab.

Once you got that part setup, try to write a simple program that buys or sells an equity from the command line .

From their own you can start exploring trading algorithms. Some are pretty basic, like when the price crosses above a 200 DMA, then buy a stock as that usually signifies an upward run, while selling if the price falls below the 200DMA as that is bearish.

Then you can read some books on price action, fundamental or technical analysis and build your own algos.