Hi everyone

Finally I got a job as a photographer, I'm a photojournalist in a company of communication and image.

I'm so glad

But again I need your advices. I have learned and got some experience doing photography landscapes, architecture some details and StilLife photos.
Now my work is very social, I have to shoot in party's and some night events, and the use of the flash is very important.
My problem is that I have no experience with shooting with flash. I got my new camera, a Canon 5D, and have 2 great lens Canon 28-70mm F/2.8 and a Canon 70-200mm F/2.8, and a Flash speedlite 580 EX II.
But yesterday I start my first job, Estoril Film Festival 2009 with the presence of Juliette Binoche and some other celebrities. I use my camera on mode P and the flash in ETTL and I get photos very dark or very brightness, and I need some tips on "How to shoot with a external Flash". In landscapes and common photography that I do I normal shoot in AV mode or M mode. But here I don't know what to use. The yesterday work didn't went wrong, but it could be much much better if I know how to use my flash.
Now if you have some advice to tell me or a link to some tips or tutorials I'll be very appreciated.
Thank you a lot
I'll get some nice features soon!