ETF (Exchange-traded Fund) can be purchased through securities brokers or online trading platforms. First of all, you need to have a securities account, which is the premise of buying ETF. When choosing a securities broker or online trading platform, we should consider its transaction cost, platform experience, available ETF types and other factors.

When you open a securities account, you can start buying ETFs. The process of buying ETF is similar to buying stocks. You can search the ETF code you want to buy on the trading platform, and then enter the quantity you want to buy to place an order. The price of ETF will fluctuate with the change of market supply and demand during the trading day, so you need to buy at the right price.

It should be noted that there are many kinds of ETFs, and different ETFs have different investment objectives and risk-return characteristics. Therefore, before purchasing ETF, you need to conduct sufficient research and analysis to ensure that your investment decision is in line with your risk tolerance and investment objectives.

For example, if you are optimistic about the future development of the technology industry, you can choose to buy a technology ETF, which will make your portfolio more inclined to the technology industry. Similarly, if you want to reduce the investment risk, you can choose to buy an ETF with low volatility. In short, before buying an ETF, you need to do enough research and analysis to ensure that your investment decision is correct.