You're going to get a lot of advice from guys who have been sparring for awhile. The thing, at your level, to remember is to RELAX, breath (especially with every technique - breath out), don't tense your muscles or fists while you are moving around, keep them relaxed till you are ready to connect. Tense muscles tire quickly. Work on your conditioning, 2 minute rounds are the longest 2 minutes of your life. Spar, spar, spar...nothing improves your sparring like fighting a lot of people often.