portal content development,how to print log and how to look up the log???

for example in a wendynpro project :

wdContext.currentContextElement().setFileResource(resource);

} catch (WDAliasResolvingException e) {

wdComponentAPI.getMessageManager().reportException(e.getLocalizedMessage(), true);

} catch (FileNotFoundException e) {

wdComponentAPI.getMessageManager().reportMessage(

IMessageFileUpDownloadComp.FNF,

new Object[] { wdContext.currentContextElement().getFileResource().getResourceName()},

true);

}

by MessageManager report the exception info but where i can see the info. and in a normal java project for portal how can i to print log info and where i can to see the info??????