In general the logs are in /YOUR_GLASSFISH_INSTALL/glassfish/domains/domain1/logs/.
In NetBeans go to the “Services” tab open “Servers”, right-click on your Glassfish instance and click “View Domain Server Log”.
If this doesn’t work right-click on the Glassfish instance and click “Properties”, you can see the folder with the domains under “Domains folder”. Go to this folder -> your-domain -> logs
If the server is already running you should see an Output tab in NetBeans which is named similar to GlassFish Server x.x.x
You can also use cat or tail -F on /YOUR_GLASSFISH_INSTALL/glassfish/domains/domain1/logs/server.log. If you are using a different domain then domain1 you have to adjust the path for that.