Well, since we are in the Rookie Training Ground, let's start from the ground up.
Planetary Conquest was a new mode introduced in Uprising 1.0 (you can find past information
here,
here, and
here). For some of us in closed beta, this was a big transition from Corporation Battles (where bids were set, and the attacking party had to agree to the terms), to the new version (territory you owned and controlled, but could be attacked at any time).
You can enter Planetary Conquest at any time, but the road to it can be quite difficult, as many view it as a sort of "end-game content". Not only do you need your own corporation name and banner to fly under (costs: 1.6 million ISK to create a corporation and further, you need to train into corporation skillbooks in order for your character to lead said corporation), but you'll need a minimum of 15 other players to fight with you. Whether you bring in people to join your cause under your corporation, or recruit "ringers" (people who will fight for and with you, but do not join your corporation), the decision will be yours.
There are a couple of ways to get your first stronghold in Planetary Conquest (or PC). You can purchase a Clone Genolution Pack for an ISK price tag in order to attack a district of your choice. The district's owner will be notified of the attack and a time will be set for the upcoming battle. On your Battle Finder screen, this battle will appear under Corporation Contracts.
However, certain mechanics may inhibit you from taking a district from the get-go. For one, currently Clone Packs give you 150 clones to attack. Many districts have a maximum clone count of 300 (or 450 with Cargo Hubs) with a clone replenish rate of 80 (100 for Production Facilities). Should you lose an attack, you get 0 ISK reward with only Salvage Loot from the battle and all clones from that battle will be lost to the winning district. Additionally, that winning defending district is unable to be attacked the following day. Should you win the battle, you receive ISK and loot, and you are able to attack the following day. However, if you are extremely careful of your clones, if you win a battle and you have more than 100 clones remaining, you have the ability of taking the district.
However, there is another way....
From what I've heard, some corps like Fatal Absolution sometimes sell of districts to other corps. The idea was in order to increase battle activity in PC, have more corps on the map from which you can attack and defend. The corp selling the district will make a verbal and or written contract and both parties agree to terms that are negotiated, which may vary. Eventually, the corporation buys a Clone Pack to "attack" the district that was agreed on. The selling corp "no-shows" to the battle and you receive the winning ISK from those battles as well as your first flag planted on the PC map.
Another thing I have heard is that General Tso's Alliance, which I am currently apart of, has a policy in which we do not take a corporation's last district. Following the idea in the above paragraph, it is currently very tough to get a hold of a district so what benefit would it be to wipe you off the map just to pay for another district that will repeat the process of the frustration and aggravation of attempting to even hold that district?
You can probably see my strong opinions in that last statement. At this point I'll step back from that scenario as it's above my pay grade.
Finally, Warbarge Strikes (Precision Strikes used in Public Matches) can be used as well as EVE support (coordination between a Dust mercenary giving strike locations after an EVE pilot connects to a beacon in space for three minutes, and an EVE pilot bringing along a spaceship fitted with special ammunition to the location above the district and firing the trigger on said Strike Requests). EVE pilots must be either apart of your corporation or your alliance which allows them to connect to the district. If they are not, they will be unable to connect to the district and furthermore unable to fire Orbital Strikes (however, you will still be able to use the Warbarge's Precision Strike which does not require EVE support). Be careful when dropping Precision Strikes and Orbital Bombardments as friendly fire is on in Planetary Conquest matches and it is possible to kill your fellow mercs and comrades with an ill-placed strike location.
In closing, I'll try and summarize up in bullet points:
* You need to make a Corporation which requires Corporation skills and at least 1.6 million to register the corporation
* Having a minimum of 15 people fight along side you, whether corpmates or "ringers"
* You can attack a district and attempt to win one by yourself, or negotiate with other corporations to "buy" a district
* EVE support is helpful, granting you Orbital Strikes, but is not required to do PC battles
Good luck out there and see you on the battlefield!