I have been asked often where can one play Go online. Actually there are many places but here are some of my favourites which I can recommend whole-heartedly.
There are mainly two types of playing Go online. One is real time games where you play with another player real time, just like you play face to face, only now you play over the internet. Typically, you log on to the server and there are usually hundreds, if not thousands of players online from all over the world. You can then set a game or join a game and start playing, usually with people around the same strength.
The other type is turn-based Go. These are not real time but players make their moves whenever they have time and log into the server. Players can agree how long to play out a whole game, sometimes one week, sometimes one month or longer depending on the players' schedule. This is like playing a game by mail in the olden days and is very suitable for people who do not have much time to spend online every day or would just like to have a leisurely pace, playing several, sometimes even a dozen or more games at the same time but taking their time to think about the moves at a more relaxed pace.
On the internet, Initially it may be hard to find an opponent because you are still new and do not have a solid rank yet but as you play more, sometimes with bots (i.e. software that plays Go which you can find as their programmers enter them into the system to "train" the software), you will gain a solid rank.
Whichever type you like really depends on your time available and the pace that you like. It can also be a mix of both.
Online real time servers
So from the four servers above, which one is right for you?
If you like a strong sense of community, meeting friends online and sometimes just chatting and playing a casual game, the KGS is a really great place. The people are friendly and sometimes there are also free lectures. Many games especially European games are broadcasted on KGS, sometimes with commentaries. You will see a lot of players online watching games especially during the European Championships.
If you like fierce competition and just wanted to drill your Go and if you are more than just a beginner, then Tygem or WBaduk is the place to go. I would recommend Tygem above WBaduk but you cannot go wrong with both. You will find many players there but beware that there are many sandbaggers there and your experience may not be good if you are a beginner. If you are a beginner and would like to play real time Go online, I still recommend you go to KGS. If you are already a pretty good player having gone past the beginner stage and is aiming at progressing the high kyu and especially the Dan level rank, then Tygem is the place for you to fight it out. Sharks are here.
Pandanet is a nice place to Go too and it has a good interface but the community there is not as strong as in KGS. If you are English speaking, then KGS is a no brainer. But if you would like to play with Japanese players, Pandanet is the place to go.
against the computer
From the above, I hope you can find what you look for. If you have any questions, please do not hesitate to ask us or your teachers at your N-World Go center. They will be very happy to assist you.