Since you don't seem to be ready to create a schematic which would clarify a lot of your project needs, please fill in the following:
For each input device you will connect,
- voltage(important)
- current(if known)
- signal characteristics - digital(what voltage), analog(what voltage range)
- what does it do/signify - temperature, humidity, water level, etc.
For each output device you will connect,
- voltage (important)
- current (important)
- control method(e.g. for a LED, it might be "digital output", for a pump it might be "digital output via mosfet, or relay)
- if you are using a relay interface board, specify
- signal input
- power input
- connection arrangement (e.g. 12V power)
If you can't do this, I simply wish you luck with your project.
That's a start.