like to access source code

[eric]

Dear Ubuntu linux developer:

I read from launchpad.net
about getting source code of unbuntu as
-----------------------------------------------------------
Alpo Turunen said on 2008-04-25: #2

If you need to get source codes of single package in ubuntu you can use
the command
'apt-get source packagename'
You must have source repositories enabled in software sources.
--------------
would you please tell me what is 
(source repositories enabled in software sources)?
command plz.

I install from 10.04, now I upgrade kernel to 2.6.35-25(by apt-get
install linux-image-x.x.x-xx)
so
should I do
apt-get source 2.6.35-25-generic
?

and

I have a piece code about locale/unicode (and output it to file by g++'s
outfile << widestring << endl;)
which is not work on my system, but worked on debian/gcc/g++ system,
confirmed by someone in gcc-help mailing list.
--------------------
#include <iostream>
#include <fstream>
#include <string>
//#include <cstring>

using namespace std;
int main(int argc, char *argv[]) {
 wstring ws2 = L"Euro: \x20ac";
 wofstream out("unicode.txt");
 if(not out.good())
   cerr << "Error opening output file" << endl;
 //const char *name = "el_GR.utf8";
   const char *name = "en_US.utf8";
 if(argc == 2)
   name = argv[1];
 cout << "trying to access locale " << name << endl;
 locale loc;
 try{
   loc = locale(name);
   cout << "Generated locale " << loc.name() << endl;
 }catch( exception &e){
   cerr << "Couldn't generate locale " << name << ": " << e.what() <<
endl;
 }
 out.imbue(loc);
 if(not out.good())
   cerr << "Error when setting the locale" << endl;
 out << ws2<< endl;
 if(not out.good())
   cerr << "Error when writing to file" << endl;
}

--------------------------------------------------------
trying to access locale en_US.utf8
Couldn't generate locale en_US.utf8: locale::facet::_S_create_c_locale
name not valid
Error when writing to file
--------------------------------
plz help on above too
thanks a lot in advance.
Eric