I planning to do make an rain sensor
When the rain sensor touch water, The led light will turn on
Not unless you read from the rain sensor, and determine that the sensor value means that the sensor is wet, and, therefore, you turn the LED on. It isn't magic.
when can turn the led light off by touching a touch sensor.
You must read the touch sensor (whatever kind you end up with), and determine that it has been touched. Then you turn the LED off. It isn't magic.
I don't know if this is gonna work, I'm new to arduino.
Being new to Arduino isn't why it might not work. Having no clue how sensors, computers, lights, etc. work is a much more significant factor, as is having hazy requirements.
For instance, pressing the touch sensor is not going to dry the rain sensor or stop the rain, so, if the sensor is wet, touching the touch sensor to turn the light off will result in the light being off for however long it takes for loop() to be executed again, and read that the rain sensor is still wet.
How do I connect the rain sensor to arduino
Are you serious?
and sent information to the computer?
and use it to turn on the led light
You said that the Arduino was supposed to turn the LED on/off.