First you need have school or be just hobbyist as me.

Choose your language or languages also platform(architecture which you will use like mac os system or windows or any other os).

Most popular for now are Java,Python,C++,C# and .NET.

If you are interested in scripting learn bash on linux or powershell on windows.

First time will be hard you will need willpower to begin writing/learning.

Create account on github and post there your programs/code.

You will need courses you can obtain them from many sources.

One is youtube others are Udemy, Coursera and guru99(free courses just like on youtube).

You can also buy books and read them.

I will post more courses if someone is interested.