How to start an FM radio station?

First of all, the most important thing is the frequency band. The FM frequency band is not an amateur radio frequency band. It is managed and allocated by relevant radio agencies. It is recommended to use the amateur radio frequency band to build FM stations. It is also recommended to use amateur radio in the HF band, because the technical difficulty and cost brought by relatively low frequencies will be lower. If you insist on building a radio station in the FM band, it is recommended to apply legally.
Secondly, I don’t know whether the subject wants to design or build by himself. If you design by yourself, it is recommended to refer to the mature transmitter circuit and antenna design, make your own board to buy components, solder and debug, if you build by yourself, there are modules and even complete sets of equipment on Alibaba and Taobao. It may be more expensive to find a radio testing agency for test equipment, and the non-FM frequency band makes the radio unable to be used for testing directly. If you have the ability and are interested in modifying the radio, it is the most suitable.
It is better to have high power.