Don't borrow money to use for stock market investment. On the stock exchange, borrowed money is known as either gearing or leverage. It is typically used either by companies (to help them finance growth), investment banks and hedge funds (to help juice their returns) or very aggressive traders. There are many spread betting (information here), options trading and day trading strategies that use borrowed money to enhance returns, but it also has a very profound impact on the risks being taken with each trade.
Pro tip: Another way to make sure your portfolio is diversified is to invest if different types of investments. Some people like to mix things up by investing in fine art through Masterworks. Fun fact – blue chip art returned 10.6% in 2018 compared to a 5.1% loss for the S&P 500. Others choose to invest in real estate through a company like DiversyFund.
Note that once a broker has identified you as a pattern day trader due to the above activity, your account will likely be considered a pattern day trading account going forward, even if you don’t continue to meet the definition. If you decide to stop day trading, you’ll want to contact your brokerage and ask that they remove the minimum equity requirement from your account.
Most of these services offer some form of free portfolio tracking - this enables you to create a portfolio and track it properly to see how you do with no money on the line. This used to be known as paper trading in the 'good old days' before 2001. This kind of exercise can be a good way to learn and play around with things without being either serious or costly.
For online platforms, websites give the user options and availability of the stock he wishes for, across all the platforms available. If he places an order, it gets stored in a database. After the confirmation of the trading account and payments, the order gets forwarded and the user gets his stock, in the form of money, transferred to his trading account.