There is a clue in the doors; they say:
Ennyn Durin Aran Moria. Pedo Mellon a Minno. Im Narvi hain echant. Celebrimbor o Eregion teithant i thiw hin.
which translates as
The Doors of Durin, Lord of Moria. Speak, friend, and enter. I, Narvi, made them. Celebrimbor of Hollin drew these signs.
Celebrimbor was an elf. Narvi was a dwarf. In the second age, there was a lot of trade between the dwarves of Moria and the elves, particularly of a town called "Ost-in-Edhil" in the region of Eregion (the elvish word "Eregion" translates to "Hollin") - essentially the entire region sort of south of the Bruinen river but north of Dunland: <img src="http://www.douglas.eckhart.btinternet.co.uk/maps-middle-earth-01.jpg" width=400">
Celebrimbor was the lord of Ost-in-Edhil; he is the one that made the three elvish rings of power (vilya, narya, and nenya - the latter of which we see Galadriel wearing in the movie - and also we see all three of them during the prologue, when Galadriel is narrating - Galadriel's got the diamond nenya, Elrond's got the sapphire Vilya, and then another elf who isn't named in the first two movies - it's either Gil-Galad or Cirdan (I suspect Cirdan will make an appearance at the end of RotK) has got the ruby Narya- Gil Galad gave Narya to Cirdan who then gave it to Gandalf before the movies take place.)
The star on the doors is the star of the house of Feanor; one of Feanor's sons was Curufin, and Curufin's son was Celebrimbor (hence the star).
Narvi just one of the dwarf crafsmen. He actually made the doors; Celebrimbor is the one that put the spell and design on them with the ithildin (the stuff that only reflects moonlight).
It's interesting backstory; essentially, back in the day, Sauron pretended he was a good guy, and lived with the elves in Eregion. Galadriel lived there too, and he knew Galadriel was powerful so he tricked the elves of Eregion into revolting against Galadriel (that's why she left and ended up in Lorien - at tha point Celeborn refused to go into the mines of Moria to get to Lorien so she left him behind). He tricked the elves in Eregion - who were really good jewelsmiths, into making the rings of power for him. However, Celebrimbor was strong enough and smart enough not to fall for Sauron's lies and so Sauron never actually got to touch and corrupt the three elvish rings of power (like he did the 9 human ones). About when they started making the three elvish rings, Sauron went to Mt. Doom & made the One Ring. Only, he learned about what Celebrimbor had done (made the three elvish rings) and got really pissed and decided to go to war with the elves in Eregion.
At this point, Celebrimbor (on the advce of Galadriel), had already given the three elvish rings of power to three of the most powerful elves around. Sauron was understandably pissed when he heard about it, and went to war on Eregion. He wanted to steal the three elvish rings (and 7 dwarvish rings also mentioned in the prologue of the movie) back for himself. Celebrimbor faught Sauron; Sauron won, tortured Celebrimbor, eventually killed him and then went to war with Elrond & his cronies further north.
Luckily, Durin (remember, those doors are called the Doors of Durin cause he was king of the moria dwarves when it was made..) sent out some dwarves to help elrond out, and Galadriel sent some of her elves from Lorien to help, but unfortunately Sauron's army was stronger and he fought Elrond back to rivendell and the dwarves & lorien elves back into the mines of moria. He couldn't get at them though because he couldn't get past the Doors of Durin.
So... he decided to march his army eastwards, towards the land where Gil-Galad (remember? he originally had Narya?) was lord because he wanted Gil-Galad's ring. Only Gil-Galad was ready for him, plus Sauron had to split yup his troops to make sure Elrond didn't come at him from behind. All the same, Sauron pushed Gil-Galad all the way East (past the shire etc.) to the Grey Havens (which will be in the final movie), and was abou