Hmmm... that's a question which may require some more questions to get to the best answer...
As far as getting J-Pop, I think asking what you mean by "getting" J-Pop is asking if you're looking for legal or illegal ways to get J-Pop. There are certainly many people who could/would tell you about sites where you could download many Japanese artists, but that is illegal activity. If you're looking for legal means fo getting this music, I could recommend some sites which sell CDs... and the Forum's banner ads have info for some good streaming Internet radio stations where you could sample some stuff for free as well.
As for recommending artists, it's good for a person who's new to the Japanese music scene to talk a little about what music in general they like. There's isn't really a set "J-Pop" style any more than there is an "American pop" style... J-Pop would encompass groups who do pop, rock, R&B, rap/hip-hop, metal, alt. rock, folk, ballads, etc. If we know a little more about your personal music tastes, we can probably make some better recommendations... unless you're like me and enjoy all different types of music, in which case let the floodgates open!
Nice to meet you... hopefully we can get you started on some good groups!