There are tons of sites which provide tutorials on Arduino. You can visit the Arduino website.
There is also another site www.freeduino.org, which has lots of links about different things to do with Arduino/Freeduino platform.
There are also many beginners books as well,
And if you want dedicated step by step DIY tutorials with lotsa of samples and interesting projects with videos
Then i can recommend you my book freeduino.begin(), the ultimate beginners guide to Freeduino/Arduino platform. There is an edition for iPad and paperback edition as well. You can visit www.bhashatech.com/BOOKS
