https://dragonagekeep.com/en_US/
This is the Dragon Age Keep, it works both as a small recap of events and to set decisions from previous games, I recommend you give it a try only after you've done some reading about them and have more of a general idea of things. You can either choose to alter things or leave the default world state that BioWare provides, it's up to you.
https://www.youtube.com/playlist?list=PL7pGJQV-jlzAYFb3DMtimVGD3kT1HEVIH
This is a playlist with a series of videos detailing the Dragon Age setting's lore and history, if you're completely new to the series I recommend you watch them, they're short and up to date. They don't really work as a recap of the previous games though, just so you know.
http://dragonage.wikia.com/wiki/Dragon_Age_Wiki
The Wiki has extensive information on all things Dragon Age, I recommend you read the plot summaries about Dragon Age: Origins, Dragon Age Origins Awakening, Dragon Age II and DA2's Legacy DLC.
This should more or less get you up to speed, remember that the Keep might be a little overwhelming if you didn't play/remember the others so, again, look at it only after you've got a good idea.