Gaining Experience in WoW

Last night I was playing WoW just to get some experience and increase my level, I started killing small monsters such as spiders and simple enemies, but suddenly I found myself fighting against level 5 enemies while i was level 2 or 3, and taking mose Quests which i dind't really understand, that might not have been the best option (or maybe it was) but the fact is that my character started to increase its level, right now it's level 4, and will continue increasing for sure since later today it's playtime, so see you in a few hours you WoW players!