How to do simple operations on the .Net side using NETLink`?

Question

I am trying to learn how the NETLink functionality works. Consider the following example:

I import the library:

Needs["NETLink`"];

I fire up the runtime environment:

InstallNET[];

I create a console so I can see things on the .Net side:

ShowNETConsole[]

I try to create an integer on the environment.

integer1=NETNew["System.Int32",4]

It fails

NET::noctor: No public constructor exists for the .NET type System.Int32.

So I just try to create an integer object first.

integer1=NETNew["System.Int32"]

I try to look what value it has by default:

integer1//NETObjectToExpression

0

If someone knows how to change the value of this created integer object from 0 to 4 then please help.

I try another approach:

integer1=MakeNETObject[4]
integer2=MakeNETObject[8]

I try to output the result of simple multiplication on the .Net side:

LoadNETType["System.Console"]
System`Console`Out@WriteLine[integer1]
System`Console`Out@WriteLine[integer2]
System`Console`Out@WriteLine[integer1*integer2]

It is not working. I get 4 and 8 but why am I not getting 32 on my console?

Also why can't I write to the console like this,

console=LoadNETType["System.Console"]
console@WriteLine["Hello world!"]

when I can clear the console like this:

consoleWindow=ShowNETConsole[]
consoleWindow@Clear[]

And what is the difference between the following lines:

System`Console`Out`WriteLine[integer1]
System`Console`Out@WriteLine[integer1]
System`Console`WriteLine[integer1]
System`Console@WriteLine[integer1]

What is the difference between backtick and @ sign? Why sometimes backtick and sometimes @ works?