Help with an Array program please?

[EternalSolitude]

I have to write this Array program a long certain specifications but I am currently stuck, if someone can help that would be great. What I have so far is posted below. What Still need to do is:
-Write a function called selsort that takes an integer array, which is guaranteed to have only positive integers, and sorts it in descending order.
-Inside selsort, create a new array. Call getMaxIndex repeatedly, and insert the max element into the new array. Set that element in the original array to such a number so that it does not come up as a max number anymore.

- and some other stuff with BagOfFruit, but I can easily finish that myself, i just need help with the above two instructions

If you haven't noticed I am no good with Arrays:o
Sorry

class BagOfFruit
{
public int numberOfApples;
public int numberOfOranges;
}

public class Lab9
{
public static int[] getFibonacci(int Size)
{
int[] arr = new int[Size];
arr[0] = 1;
arr[1] = 1;
for(int i = 2; i < Size; i++)
{
arr[i] = arr[i-1] + arr[i - 2];
}
return arr;

}

public static int getMaxIndex(int[] arr)
{
int maxIndex = 0;
for(int i = 1; i < arr.length; i++)
{
if ( arr[i] > arr[maxIndex] ) maxIndex = i;
}
return maxIndex;
}

public static int selsort(int[] arr)
{

}

public static void main(String[] args)
{
int[] a = getFibonacci(10);
System.out.println(java.util.Arrays.toString(a));

int[] BagOfFruit = new int[3];

}
}

[Eranga]

If you are not good with Java arrays, I think it's better to refer some materials before do this assignment.

Here is a link.

Follows all explanations and examples on that above page. It's really helpful to you.

[Eranga]

Here is a simple example for the first part.

public class WorkingWithArrays {

    public static void main(String[] args) {
        int[] arr = new int[10]; // Initialization and declaration of an array
        
        // Adding elements(populating)
        arr[0] = 2;
        arr[1] = 4;
        arr[2] = 6;
        arr[3] = 1;
        arr[4] = 0;
        arr[5] = 9;
        arr[6] = 7;
        arr[7] = 8;
        arr[8] = 3;
        arr[9] = 9;
        
        // Check for negative values
        for(int i = 0; i < arr.length; i++) {
            if(arr[i] < 0) {
                System.out.println("Negative value is found. " + arr[i]);
                System.exit(0);
            }                
        }
        
        // Call the selsort method
        new WorkingWithArrays().selsort(arr);
    }
    
    private void selsort(int[] arr) {
        
        java.util.Arrays.sort(arr); // Sort the array using Java API
        
        // Display the result to check
        for(int i = 0; i < arr.length; i++) {
            System.out.println(arr[i]);
        }
        
    }

}

[EternalSolitude]

Thanks for the help, I really appreciate it