Hints

1. Determine the total number of birds that you counted so far

Refer to the exercise introduction for an example of how to use a for loop to iterate over an array.
Use a helper variable to store the total count and increase that variable as you go through the array.
Think about the correct initial value for that helper variable.
Refer back to the array concept to recap how to retrieve values from an array.

2. Calculate the number of visiting birds in a specific week

This task is similar to the first one. You can copy your code as a starting point.
Think about which indexes in the array you would need to take into account for week number 1 and 2, respectively.
Now, find a general way to calculate the first and the last index that should be considered.
With that, you can set up the for loop to only iterate over the relevant section of the array.

3. Fix a counting mistake

Again, you need to set up a for loop to iterate over the whole bird count array.
This time you only need to visit every second entry in the array.
Change the step so the counter variable is increased accordingly after each iteration.
In the body of the for loop you can use the increment operator to change the value of an element in an array in place.