I have a solenoid valve just like this and its rated 120 VAC/26VA (3 prongs, one for ground) . I also have a
horizontal level switch for liquid like this
http://germes-online.com/direct/dbimage/50279527/Level_Switch.jpg with
rating 120 VAC/0.28 A (the switch will connect when the water level
reach the target) normally open.
How can I wire them so that when the level reached the plug valve will
close and water will not flow into the tank? The switch is inside the
tank and the valve connecting the pipe for feed water.
I dont know what you are trying to accomplish. You didnt let us in on
the brand and type, but it sounds like a front loader Duet or something
like that. Are you trying to defeat the intention of the solenoid or
what ? If so, forget it. Obviously you dont have a clue about this
complicated washer.
From power, go to the float valve.

From the other side of the float valve, go to your solenoid.

From the other side of the solenoid, go to neutral return.
When the float valve is open, the switch will be open, and the
solenoid will be open. When the float rises and closes the switch, the
current will flow closing the NO solenoid to engage and shut off your
water flow.

MORE NEWS