Assuming you have access to them (the properties you've declared are protected), you use them like this:
Person tom = new Person();
tom.Title = "A title";
string hisTitle = tom.Title;
These are properties. They're basically pairs of getter/setter methods (although you can have just a getter, or just a setter) with appropriate metadata. The example you've given is of automatically implemented properties where the compiler is adding a backing field. You can write the code yourself though. For example, the Title property you've declared is like this:
private string title; // Backing field
protected string Title
{
get { return title; } // Getter
set { title = value; } // Setter
}
... except that the backing field is given an "unspeakable name" - one you can't refer to in your C# code. You're forced to go through the property itself.
You can make one part of a property more restricted than another. For example, this is quite common:
private string foo;
public string Foo
{
get { return foo; }
private set { foo = value; }
}
or as an automatically implemented property:
public string Foo { get; private set; }
Here the "getter" is public but the "setter" is private.