You will need a camera that can send pictures to the internet, these are usually called ip cameras. There are lots aimed mainly at the security market, a search for waterproof ip camera or outdoor ip camera will lead to hundreds of products. I can't recommend a particular model as they change so often and the technology improves.
You will need to get power to the camera. Having the power supply indoors and running the low voltage cable to the camera is safer but make sure you have cable designed for outdoor use. There are solar powered cameras available but these are designed to be used as a motion activated security cameras, if used 24/7 the battery won't last.
You will need to connect the camera to the internet. If the camera is in range of your WiFi then great, if not then you will need to run a cable out to the camera, again one aimed for outside use,. You will need to check that your proposed camera has a network socket, some are WiFi only. You can do network and power in one using something called power over ethernet (POE), but you will need to check the camera can use POE and that your home network can provide it, most ISP provided hubs will not, you can buy adapters that will provide POE. POE can be better if you have a particularly long or tricky cable run.
The live streaming itself can be done entirely by YouTube, there are many tools provided, or your particular camera may come with its own software.
