Hi Lizachka!
Firstly, I hope you've taken a look at this website:
www.ibiza-spotlight.com
The main Spotlight site has a wealth of information, including descriptions of the main resort areas and the main clubs, hotel info & reviews, etc. You should take the time to look through it.
The main resort areas are San Antonio, Playa den Bossa, Figueretas and Talamanca, though you can also stay in Ibiza Town and there is the "quieter" side of the island with Santa Eulalia, Es Cana, etc. Detailed descriptions of each are on the Spotlight site.
Most of us here in the forums stay in either the Playa den Bossa/Figueretas area or in San Antonio. But we kind of need to know what you're looking for, when you're going, etc. to make a recommendation.
Re: flights, where are you flying from? If the UK, people often recommend this site:
www.skyscanner.net