To get started with Spring, visit Downloads to get the latest version. It comes with some AIs and with SpringLobby, which you can use to play, chat and download games and maps.
If the download fails, or if no games/maps show up, you should check that your lobby has found your Spring install. With SpringLobby, click edit -> preferences -> Spring, and make sure that it has the correct paths.
To start a single-player game, use your lobby. Go to the Single-Player tab. Select a game, map and AI and click "Start".
Some AIs don't work with all games. If the one you pick builds nothing, try another!
To play online, you need the latest version of the Spring Engine. To join matches, look for the "battles" or "multiplayer" tab in your lobby client.
See the dedicated page Playing on a lan.
Useful Hotkeys, Etc.
For the default keyboard layout please look at the Keyboard page.
The Spring Forum
Your question not answered here? Got problems?
Game Specific Questions
If you have a question or problem with a certain gameplay mechanic in a game, you can talk about it at the game's subforum
If Spring crashes/hangs, please look at the FAQ.