I really need help!

well, you'll need to attach your code for us to see exactly what's wrong with it, but your code should look something like this

BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int sum = 0;
int count = 0;
//this part is given in the task requirements
while (true) {
    int number = read the number;
    if (check whether the number is -1)
        break;
else{
sum+= number;
count+=1;
}
}

Then you should be able to calculate and display the average

you will need to attach solution because we can not see your code otherwise.