Discussion on the Continuum Wiki is greatly encouraged, but it is advisable that you are aware of where you should be initiating certain topics. For rules and other policies regarding involvement in the community, read our policies or our other guidelines.
Comments are basically that.. comments and thoughts you want to share about the topic of that particular page.
Blogs are used to start a discussion, or maybe to write out something you've been wanting to let out about the show, and you may want others to weigh in or hear you out. Although quite similar to the forum (see below), blogs are different in that it may be a personal post, and not necessarily for discussions. You may even share a story (related to the show or your experiences with it, at least) or fanfiction.
Forums are used to initiate discussions about certain topics. You can start this if you want to have others to respond and give their opinions, as well. This can be anything, from opinions, to theories, to reactions, etc.
Use message walls if you want to contact a particular individual user, or a certain number, somehow privately. If you have questions, or maybe an issue you would like to settle.
At this point, it is doubtful that the Chat feature will be used, given the wiki's silent state. The only wikis I have seen with users actually using the Chat feature are those wikis which are very active and has several invested users.
Nonetheless, the Chat would be a good place to hang out with and meet other users and get immediate responses. A great chance to use the Chat is when users have agreed to watch episodes together and discuss live. It'll be like hanging out with friends in the living room to watch Continuum when it's on. ;)