Void Main() = This is the main part of the script or code. It\'s the base, if you will... you can have procedures within the Main code, but there\'s nothing outside Main itself (except global declarations and include files).
Text prefixed with // are comments. These are ignored by the program and appear purely to describe things to the programmer.
{ (an open bracket) tells the program that a new procedure is starting. All code that follows a { and ends with a } is one procedure and is generally not affected by other procedures.
\"int\" means Integer. This forces the program to believe that the value is numeric only.
\"sum\" is a mathematical instruction. It explains itself, really.

\"cout\" is a text output. It\'s what the program is saying to you. Similarly, \"cin\" is an input. In your example code, your text input (which can only be a number, according to the \"int\" ) is being designated as \"Value1\" so that the program can easily distinguish between it and other items.
sum = value1 + value2 + value3; This line is an instruction to the program. It is telling it to add up the three values based on what you input for each of them.
The last line of code is the final instruction given to the program. It tells the program: \"Say \'The sum is\', then say the value of the \'sum\' line, and that\'s all.\"
Finally, this procedure is closed with a }.
My terminology might not be perfect here, but I hope it helps a little.
