you need a mic in order to talk over teamspeak but you can always come in and at least listen to the commands of everyone else, you can get a good cheap mic for about 5-15$ i suggest just getting a desktop mic, unless you want to spend 40$ for a good headset.
I used to have a desktop mic and highly recommend a headset one. It's just hell of lot more convenient and you'll be understood better. Friends of mine i have a Sennheiser headset. Ranging from 15$ to 65$ and are all happy with em.
just call me phil on ts, ingame, wherever. i'll even respond to phil in real life. wooohooo!
untill you get your headset make sure you make good use of your ingame communication measures and at least have a means to hear the commands being issued over TS otherwise you will be lost, not knowing what to do..