I don't have the item to do it.
I don't have anything. I'm barely at my starting equipment, this is the beggining of the game for fuck sake and strategies either talk about acquiring a sword by exploiting a drake, or summoning an NPC.
Other than that, it's all about getting lucky enough to kill one before the other decides to hurt you. That's the strategy: luck.
Fuck this.
Really, I'm watching videos of how to do it, and it's always this phrase: "if you're lucky".
The main attraction of this game was that it was hard, but you could do it by being focused and not making mistakes. Here it is chaos, you have to "be lucky" enough to kill one before the other killing you.
Fick this 2.
You most definitely have at least 1 Humanity item in your inventory, the game puts a few in your path in the beginning stages.
Equip it, use it, and your active Humanity counter (top left corner of screen) will go up. Then you can sit down at a bonfire and Revert Hollowing (become Human). Once you do this, then you'll be able to see the signs of other players and bring someone in. Also, for the Gargoyles, right before the fog gate, there's an NPC sign you can call on to help you.
Popular places to find sings are either around the Sunlight Altar (bonfire underneath the red drake on the bridge) and on the stairs leading to the boar from Parish; or in front of the entrance in the church of the Gargoyles, the one leading towards the Garden and smith Andre.
And if you're going around the world killing stuff but not killing the bosses of those areas -- after a while you'll receive active Humanity (your top left corner counter will go up). You can use this Humanity the same way as above -- bonfire, Revert Hollowing.
Regarding your issue with the Gargoyles... Upgrade your weapon (or the highest damage weapon you have and can use) to +5 (you can buy the Titanite Shards needed for this directly from smith Andre), get a 100% shield, get 1 humanity and summon either a player or the NPC.
The +5 weapon is important as you gotta have some high DPS to take as much life as possible out of the first Gargoyle until the 2nd one appears -- it simplifies the fight to fight one at a time, instead of both all the time.
And lastly, you can get Humanity by using the White Sign Soapstone yourself (you get the WSS by talking with the guy looking at the sun at one end of the bridge with the red drake). You don't have to be Human to use the White stone, you can also do it while Hollow. Sign down in one of those places mentioned above, and someone will call you in their game. Help him beat the Gargoyles, and you'll get a lot of souls and Humanity.
/edit
Listen to this man, by the way. The Claymore especially, it's a simple thing of beauty and it might carry you through the whole game if you keep upgrading it. The moveset is very good as well, and balances nicely the damage & the speed, the horizontal & the vertical moves.
Do you have the halberd? Go to the blacksmith and upgrade it to +5. It's very useful in this fight.
You can also pick up the Claymore (on the bridge where the red dragon was) and upgrade it. It's an awesome weapon.