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.
Edit- You need an Origin account for this, just so you know. You're probably going to want to use it if you're getting Inquisition though so better get familiar with it now.
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.