How to access a variables and functions of a specific class from another class in C#

You can call a variable of first class from second class by creating Class constructor it is not a static class for static class you can use

public class First
{
    public string Name {get;set;}
}

//calling it from another class
class Program
{
    First frst= new First();
    static void Main(string[] args)
    {
        frst.Name = "Sam";
    }
}

Check MSDN
base class with property:

class Person
{
    private string name;  // the name field
    public string Name    // the Name property
    {
        get
        {
            return name;
        }
        set
        {
            name = value;
        }
    }
}

Check this url Auto-Implemented Properties (if advanced work on "name" isn't needed):

class Person
{
    public string Name { get; set; } // the Name property with hidden backing field
}

Accessing class property from another class

Person person = new Person();
person.Name = "Joe";  // the set accessor is invoked here                

System.Console.Write(person.Name);  // the get accessor is invoked here