Hi

can edit/add quests?

Thanks

huh?

if you are on pc, you can use the console to advance quests. you can even use the console to start a quest. until the creation kit is released you can't truly edit any aspects of the game though.

for a list of console commands: http://www.uesp.net/wiki/Skyrim:Console

for quests and their id's: http://www.uesp.net/wiki/Skyrim:Quests

Just about every post you make is a modding question. You should really post your questions in modding instead of Cheats, Hints and spoilers. You have a better chance of getting them answered there.