You cannot supply loads like a solenoid with an arduino at all. The arduino output pins like small currents, not big currents.
Even more than a few LED's is too much.
You need to learn how to use small currents from arduino to control external transistors or relays to supply
power to the other devices. If you have a big enough 9V power supply, you can take current from there direct
to the output side supply of the relay or transistor. That current doesn't go through the arduino at all.