To get you started out on the game, choose one or both options:

1) Find a veteran that you know/ get to know who can teach you the basics of the game.

2) (STRONGLY RECOMMENDED) READ THE WIKI! The link is right up there ^^^ and there's a guide for almost everything. For those too lazy to look it up yourself, here are links XD
Starting out: http://wiki.spiralknights.com/Starting_out or New player briefing: http://wiki.spiralknights.com/New_Player_Briefing
Swordsmaster: http://wiki.spiralknights.com/Swordmaster_Guide
Gunslinger: http://wiki.spiralknights.com/Gunslinger_Guide
Bomber: http://wiki.spiralknights.com/Bombing_Guide
Shield usage: http://wiki.spiralknights.com/Shieldbearer_Guide
Strategies: http://wiki.spiralknights.com/Strategies

G'luck y'all!