How do I apply for OCS, what kind of documents would I need, and what should I expect from it?

There's a MILPER announcement for OCS every year. In the Air Force, part of their briefing is that they tell you the first step in the selection process is figuring it out on your own by researching the regs and publications. They don't say that in the Army, but it's implied. If you're going to be an Officer, you're going to be dropped into a lot of situations you know nothing about and be expected to figure it out quickly.

If you access through OCS you don't get to pick your branch. Unless you are branching aviation, but if you want to fly you are better off becoming a Warrant officer. You can't branch Special Forces, you have to branch something else and then try out for SF. You need to be at the top of your game if you do that because unlike the enlisted side, there is a max number of SF officers allowed to branch each year.

Your recruiter wasn't lying but they weren't truthful either. Recruiters have one job. Recruit candidates. A NG recruiter will sell you a product. An Officer selection recruiter will sell you their product and your recruiter sold you their product. They have quotas to fill at the end of each month.

Have you spoken to your retention NCO for information? Have you contacted an Officer Recruiter? This is where you need to start.

First question, is your GPA competitive and I assume your ASVAB Score is high enough to qualify? Have you been in the unit long enough to get evaluated? No Flags?
Talk to your Commander, you are going to need his endorsement. Then start getting your packet together, Transcripts, Awards, copy of Birth Certificate, all of which you should have from enlisting. You will have to write a paper on why you want to be an officer and how wonderful you would be at it. Get letters of recommendations for your command up as high as you can get it. Get LOR's from any prominent civilians, professors, etc. Send your packet to the board and hope for the best.
Bad news. OCS sucked. At least during my day, think of it as all the meaningless harassment that you took during Basic Training, but being done by people (The TAC's) that don't care if you pass. Hopefully some of that has gone away. I didn't find the Academics to be very hard and I had come out of an Infantry unit, so I was in better physical shape the the majority of the class and all of the TAC's. If you want it, just keep your head down and soldier on.
Bad news number two. OCS Officers are needs of the service. You get a wish list, but if they don't need anyone in those Branches, you get what they pick. I have no idea how hard it is to get on the Aviation side of things, but you get to be Special Forces as an Officer the same way as you do Enlisted, apply and pass Selection after you are Branch Qualified.