I have arma 2 installed in steam and I have the gt lite app and running. I select arma 2 and launch and all it does is bring up my steam and the community page. How do I get it to launch the game and join the server i selected please?

It was solved on another thread. Gametracker has a bug that it has the app ID for the game wrong, so you have to change it.

BEFORE YOU DO THIS BE SURE TO MAKE A BACKUP OF GAMETRACKER
Find the folder you installed GameTracker to, and make a backup of gamelist.xml, along with another copy of it. This copy will be the one you will change, because for some reason it wont let you edit it while its in the folder. Open the copy, press Ctrl + F and find type 33900. This should lead you to the line that opens the game.. It should read:
"<run_cmdoptions>-applaunch%2033900%20%5BRUN_EXTRA_ARGS%5D%20%5BRUN_NETWORK_ARGS%5D</run_cmdoptions>"
Find the 33900 and change it to 33910 and save the xml file.
Then, take the file and replace it with the one that is already in the folder. Restart Gametracker and it should be working fine