You can't join tournaments yet in the mobile application. Though, from what I understand (have never tried it yet) is that you can join a tourney on the web-interface, close the Live window/tab and get on Live on your device. When the tourney starts your games will show up on the app.
Not 100% that is the way it should work or it won't stop working in the future, just that it supposedly works.
Hello,
I would like to play in tournaments and "play the computers" on Chess.com. Has anyone found a way to do this on the iPad or iPhone? I'm playing the computer..."Computer 1- Easy" to build up my speed and coordination with my mouse hand. I wrote about playing on my iPad for the last two years! Fun, but not good if you want to play bullet, blitz and enter tournaments. So, I hope Chess.com finds a way to make this hasppen. I like using both the iPad and the desktop. Finding the right mouse is another story, lol! Take care.