Trying to organize an array of structs in C

I'm a relatively new programmer working with structs for the first time in C. Currently I'm tasked with organizing an array of structs based on an int contained within the struct. I have the merge sort algorithm implemented and working with an array of ints, but I am confused on how to sort the ints when they're within a struct.

So far I've tried making an array containing only the ints I'm concerned with. However, then the original array of struts isn't sorted, just the new integer array.

I am assuming your struct looks like this and you have an array of the struct

typedef struct {
    int value;
} MyStruct;

MyStruct arr[] = {
        {10}, {7}, {8}, {5}, {2}
};

apply your sorting algorithm to arr[] where the each number in the array can be accessed by arr[i].value so you can use the numbers to sort the array

Though not asked in a clear way, I guess your question is 'sorting an array of structures, with an int in the structure as the key'.
And there are other 'contents' in the structure but not the key.
If so, you should sort the struct instead of only the key.
Here is an example:

typedef struct
{
    int key;
    int other_value;
}ele;
#define SIZE 5
ele arr[SIZE];
void example_bubble_sort(void)
{
    int i; int j;
    for(i=0;i<SIZE;i++)
    {
        for(j=0;j<(SIZE-i - 1);j++)
        {
            if(arr[j].key > arr[j+1].key)
            {
                ele temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
            }
        }
    }
    return;
}