To start with mining, you need to acquire mining hardware. In the early days of bitcoin, it was possible to mine with your computer CPU, or with a high speed video processor card. Nowadays such systems are no longer in existence.
Custom Bitcoin ASIC chips offer performance up to 100 times capability of older systems have dominated Bitcoin Mining Industry. Bitcoin mining with anything less than the modern capacity will consume more electricity than you are likely to earn. Therefore, it is better to mine bitcoins with the best bitcoin mining hardware built specifically for the purpose.
Another option will be to purchase Cloud mining contracts. This is great and simplifies the process. It will be available by the third quarter of 2018.