Even though your question is very very simple, it will be very complicated for beginners, especially when buying Bitcoin for the first time. To convert fiat to Bitcoin requires a few very simple steps, such as choosing a trusted exchange available in your country and then depositing an amount of money that you are ready to invest. Some of the effective steps suggested by other users in previous comments can be very helpful in getting started buying Bitcoin. However, remember, never store your Bitcoin on an exchange, as it is very risky. Choose a wallet where you can control the private key to store your Bitcoin, such as Electrum and several others.

It's a bit complicated at first, but then it becomes familiar and over time you'll become accustomed to everything related to Bitcoin, from how to buy it to storing it in a safe place.