gistfile1.txt

public struct MyStruct
{
   int ID {get;set;} //2 bytes?
   int Header {get;set;} //5 bytes?
}

public MyStruct ReadFile(string file)
{
    MyStruct m = new MyStruct();
    using (var fs = new System.IO.FileStream(file, FileMode.Open))
    {
        Byte[] bID = new Byte[2];
        m.ID = fs.Read(bID,fs.Position,bID.Length) > 0 ? bID : 0;
        //etc
    }
    return m;
}