Hello, I'm doing an assignment for a web design class. I'm developing some javascript that allows the user to input a temperature in Farenheit and receive a Celsius conversion. Here's what I have so far.

PHP Code:
//in HTML document
<p>Please enter the temperature in Fahrenheit.</p>
label for="textInput">Temperature: </label>

input type="text" name="textInput" id="textInput" value="" />

p><input type="button" value="Convert" onclick="convertTemp("textInput", "textOutput")" /></p>

label for="textOutput">In Celsius: </label>

input type="text" name="textOutput" id="textOutput" value="" readOnly=true />

//in javascript file
function convertTemp(inputIdoutputId) {

input parseInt(document.getElementById(inputId).value);

document.getElementById(outputId).value = ((input 32) * (9));

I'm having a real hard time grasping how a function receives information and returns it, so how I'm supposed to get the function to output to the "celsius" text box is eluding me. Some help, if you please?