xrc, no you do not have to start a match to enter a tournament.
In live chess you will see your main chat tabs and just above that you will see two tabs. The "new game" tab and the "tournaments" tab.
To see all current tournaments, simply click the tournaments tab. then you can select a tournament that you would like to enter by clicking "join".
It's as simple as that :-)
Do I have to start a match of live chess to be able to see all the tournaments and join in one of them?