Pokemon Diamond/Pearl Battle WiFi HELP

Haloo guys..
How to fight another friend pokemon using wifi??my wifi was work perfectly, i can use GTS without any problem
i have my friend code..
last, where to fight my friend??is it diffrent with battle tower??
Can someone help me??
Thankx alot.. :)

You need to go into a pokemon center.

its in the pokemon center second floor talk to the third girl :D

ive already do that,
than theres an option..-Invite
-Disconnecti choose invite and click the single battle but nothing happens..
my friend not see me either..What should i do??

Its work..
Its work..im sorry, to bother everyone..
thx for the reply ^^

no problem :)