Sava/load file using XML

Can someone tell me how to save these two arrays into an xml file?

public bool[,] boughtItems = new bool[5, 16];
public int[ ] selectedItems = new int[5];

It is important that the code can activate some kind of output method so I can load default settings if the file is not found. Here is a sketch for what I want:

Load:

if (file exists){
load file?
}else{
LoadDefaultFile(); //i’ll take care of this function
}

Research how to use System.Xml. Here’s a previous thread on the topic.