Here after a working procedure that send a TCP traffic:

proc ftptraffic { src dst starttime } {

global ns_ node_

set tcp($src) [new Agent/TCP]

eval \$tcp($src) set packetSize_ 60

set sink($dst) [new Agent/TCPSink]

eval $ns_ attach-agent \$node_($src) \$tcp($src)

eval $ns_ attach-agent \$node_($dst) \$sink($dst)

eval $ns_ connect \$tcp($src) \$sink($dst)

set ftp($src) [new Application/FTP]

eval \$ftp($src) attach-agent \$tcp($src)

$ns_ at $starttime "$ftp($src) start"

}

puts "\nTraffic: ftp"

ftptraffic 8 9 $appTime1

Get used to with the source code for ns2 ... there is a good documentation available .... you need to understand some  C++ code and then you can write some function in those source files which inputs and outputs a message. recomplete the ns2 source and things should work ... but first you need to know the source code of ns I feel

you may refer this link  for getting  some idea 

http://ramakrishnamundugar.blogspot.in/p/tcl-script-to-demonstrate-message.html