I highly recommend you go into the Sad Panda Cubs channel or the OrganizedPvP channel with this question, as the players there will do their very best to help you get involved and active in PvP.
You may get to either channel by clicking the three-person icon beside your chat bar, selecting Chat Settings, clicking the Channel tab on top of that page, and entering "Sad Panda Cubs" or "OrganizedPvP" in bar, (without the quotations marks,) then clicking join.
Once you have done this you will find a wealth of experience and knowledge waiting to dump itself on you. Where you can currently select Zone, Team, or Local you will have the new channel selections available. Select your new channel, and type hello, then ask your questions.
My only advice is that gear won't be as significant an issue as many players, (myself included at one time,) think. PvP is more about teamwork and communication. If you're willing to learn these two facets of the game, you will discover a world of fun waiting for you in STO.
Equipment Wise: Any cruiser is usually best off with a set of beam arrays. Low-firing arc weapons are tempting due to the Galaxy-X phaser lance, but ultimately - you don't ahve the turn rate to use htem very often, so you're better off broadsiding most of the time. I could see putting in a single Dual Beam Bank, since the difference between 8 and 7 beam arrays hitting a target is not that big, and it may allow yo uto use Beam Overload.
Anyway, the most complex and most important thing about a ship build is usually the Bridge Officer Powers you have access to.
A Cruiser's greatest strength in PvP is always its healing capabilities. He's a healer. He isn't a tank in PvP, since people only shoot at the target that seems weakest, not the target that can heal itself all the time. Of course, sometimes people like to shoot at Galaxy-X because many people flying them are bad and they don't build their ships for healing.
The most fundamental things to know about powers
Every ship should probably equip 2 Emergency Power to Shields. EPtS gives you shield resistance and some shield healing, and shield power (which gives you shield healing and shield resistance!). If you're very "egoistic", take two EptS3. But I say egoistic, because high level slots reserved only to help yourself means you won't be a good healer. But maybe it will help you at first to even figure out what's happening in PvP. I don't recommend it in the long run, it's "training wheels". 2 Emergency Power to Shields may be a little weak, 2 EptS2 or 1 EptS1 and 1 EptS2 may work.
Whatever you pick -2 EptS means you can run them back to back, with no gaps, always protected, always at least somewhat ready for any surprise attacks.
Distributing SHield Power is important. If you click on your ship's paper doll in the UI, you can distribute shield power evenly between the 4 facings. THis is often a good idea. Shield heals always apply healing to each facing seperately, that means if a shield facing is full, you're wasting heals. On the other hand ,if a shield facing is zero, your shield resistances do not protect you from any damage and kinetic attacks (torpedoes) hit your naked hull. You don't want that.
You can help your shield power distribution even more if yo uslot Tactical Team. It will move shield points from all facings to the facing that is taking damage. That is very useful to deal with damage spikes from Escorts.
For healing, these powers are useful:
Engineering Team II or III (Good uptime, instant heal, recovers subsystem.
Auxillary to Structural Integrity Field (Excellent uptime, instant heal and hull resistance)
Extend Shields (Provides allied target with great shield resistances and minor sheal. Drawback is that you need to stay within 7.5 km - but if you can, it's totally awesome)
Hazard Emitters (Hull Heal over Time, best hull heal to deal with continual damage, not good against spikes. Deals also with plasma fires and warp plasma slowdowns. Weak uptime.)
Transfer Shield Strength (Shield Heal over time. Weak uptime.)
Aside from the aforementioned OrganizedPvP and Sad Panda Cubs chat channels, a resource I would like to shamelessly plug is my Foundry mission that includes a description and some thoughts to every Space BO and Captain power in the game and how it works for PvP - including some training missions where you can hopefully learn a little bit before you dive in head first into PvP. I believe it's called Mustrums' Space Combat Simulator or some such. Best to search for my handle (MustrumRidcully).
I have a dreadnought. I'm engineer. I'm not a tac.
Could you tell me if my dreadnought has good gear for PvP against federation ship?
Could you give me some advices? Thanks in advance.
1 DBB Antiproton MkXII very rare anti borg
1 Cannon Antiproton MkXII very rare anti borg
1 Beam array Antiproton MkXII very rare anti borg
1 photonic torpedoes MkXII very rare anti borg
2 Turrets Antiproton MkXII very rare anti borg
2 Beam array Antiproton MkXII very rare anti borg
Personally I'd recommend going for a 7-8 beam array build. Forward mounted weapons are fine when fighting cruisers, but you'll also be facing very maneuverable escorts, which you'll have a hard time keeping in your forward firing arc.
That said, 6 beam arrays with 2 dual heavy cannons should give you roughly the same DPS in your forward arc as your broadside.
I'd drop the nadeon detonator and replace it with the borg console (gotten from the assimilation mission). If you haven't already got them, I'd also highly recommend getting the borg engines and deflector (not the shield). Three pieces of the Borg set will mean you have a chance of getting your hull and/or you shields healed.