first of all, arrays are declared like this:
int arr = new int;
arrays are tools used to sort or collect data. instead of creating 10 variables you can declare an array with 10 indexes.
int means the type of the array e.g. int, double,string
 means how much dimensions will be in the array. e.g. int(3 dimensions)
next is the name of the array e.g. arr
new is a syntax word for declaring it
int represents the type of the array you declared beforehand.
then  represents how much indexes you would like to have in the array.
int arr = new int would have 10 indexes.
int arr = new int would have 9 indexes in the first dimension and 5 in the second dimension.
you can access array by doing that
arr = 5;
doing that will make the index 3 of the array to be worth 5.
you can print arrays by doing stuff like this.
for(int x=0;x<arr.Length;x++) Console.WriteLine(arr[x]);