>> int integerVariable[noOfArray];
First, you moved this line up in your code. As I said, it is technically illegal anyway, but now it is worse because noOfArray has not been initialized. Just come up with a maximum number and use that as the size of the array instead of the noOfArray variable. Continue to use noOfArray later in the program as you currently are, though.
>> There is something wrong with this line
Yes, there is. At that point you are attempting to call a function. When calling a function, you pass variables as arguments to the function. You need to change that line to pass the array variable and the noOfArray variable to the function. To pass a variable you just put the variable name.
Another thing to remember is variable scope. If you declare a variable inside the main function, you cannot use it inside another function. For example, you declare allNumbers at the top of main, but only use it inside averageFunc. You should declare it inside averageFunc. In general, you should declare and initialize variables just before you want to use them.
Finally, you've got a decent amount of code there. It is much easier to work through problems one at a time, though. You should be adding a little bit of code, then compiling, then adding more code, etc. This way, you won't have to deal with so many compiler errors at once, and it will be easy to narrow down what changed caused the most recent error.