It's very different from PvE and it's hard to learn without someone knowledgeable with you explaining what's going on. You can look up arena guides/videos for your class to try and get a general idea but PvP is also about knowing what everyone else can do on their class too and that takes time/experience. There's no secret to it but you're competing against years, maybe even a decade+ worth of experience in some cases now.

If you're in a guild try to find someone with a bit of rating and see if they'll at least do some skirms with you or maybe even run 2s on an alt or something. Even if you're still losing having someone capable of explaining wtf just happened when that paly/druid/mage/rogue etc killed you in an instant goes a long way towards making it a useful learning experience.

If you're a solo player though and undergeared to boot then good luck because finding a team outside of yolo rbg groups will be hard with no experience.