Is there a free web site where I can manage my trip and update it with pictures and notes?
Not sure what you mean by "manage". There are several sites where you can keep a free blog. I use wordpress.com, but a lot of people use blogspot, and travelpod.com is popular with some travelers.
If you're talking about pre-trip, look into something like tripit.com. You can keep track of all the itinerary details in one place and add phone numbers, addresses, notes, etc. I'm using it now for my upcoming Italy trip, mainly because it has a free phone app so I can have everything electronically with me and accessible even offline.
If you're talking about during the trip, for posting pictures, etc, I agree with the post above...there are lots of free blog sites you could use.