Hi,
Sorry I didn't see this earlier. I can't say that there's really an "event planning" area, unless you're looking specifically for weddings or conventions.
What about planning is it that you like?
Most positions similar to an outside company's event planning department would fall under either Sales or Services. Sales is all about getting the initial contract signed, giving FAM (familiarization tours) to show the locales and securing the business.
The services side is going to be more focused on adding on components to the event, then delivering the event when it happens.
Each of these areas have multiple roles in each.
If you can tell me what qualities you feel most strongly relate to events and where your interests are, I might be able to answer a few questions and get you in the right direction.
Pertaining to hierarchy, associates, assistants, coordinators and inters start the chain. THey're responsible for lots of things like preparing contracts, accepting ticket orders, basic client communication (on behalf of their sales or services manager), accepting incoming and/or prospecting calls and so on.
The next link in the chain would be a sales or services manager. These people typically have 5-10 years of experience as a sales/services coordinator.
Beyond that would vary based on which area you're speaking of.
Hope that helps.