log4j WARN No appenders could be found for logger

Hello,
I want to create client application and every time I type:
WSDL2Java.bat -uri
http://localhost:8080/axis2/services/HelloWorldService?wsdl -o client

This error happen:
Using AXIS2_HOME:   C:\Users\Nicole-VM\Desktop\AXIS2\axis2-1.6.2
Using JAVA_HOME:    C:\Program Files\Java\jdk1.7.0_07
Retrieving document at '
http://localhost:8080/axis2/services/HelloWorldService?wsdl'.
log4j:WARN No appenders could be found for logger
(org.apache.axis2.description.WSDL11ToAllAxisServicesBuilder).
log4j:WARN Please initialize the log4j system properly.

I searched a lot to solve it but I don't know how to solve this WARN. I'm
new to Axis so please any help would be appreciated?
-- 
*thank you for your time

Sincerely
Areeg Samir*