Avril Lavigne wed Sum 41 frontman Deryck Whibley on Saturday afternoon at a private estate in Montecito, Calif., a source confirms to PEOPLE.

At the outdoor, non-denominational ceremony, Lavigne was walked down the aisle by her father, John,

to Mendelssohn's "Wedding March." She wore a Vera Wang gown and carried a bouquet of white roses.

The couple said their vows under an awning decorated with white flowers in front of 110 guests, including

 family and friends from their native Ontario.
Once the groom had kissed the bride, guests tossed rose petals at the newlyweds as they walked back up the aisle.

After the wedding, guests were treated to an outdoor cocktail hour before the reception, including a sit-down dinner, under a tent on the estate. In contrast to the all-white ceremony, the reception had a red theme, with centerpieces of red roses and other flowers.

The couple's first dance was to the Goo Goo Dolls' "Iris."

Lavigne, 21, and Whibley, 26, have been together for two years, and became engaged in Venice, Italy, in June 2005, while Lavigne was on the last leg of her European tour.

In late 2004 Lavigne started sporting a small pink heart-shaped tattoo with the letter "D" on her right wrist, supposedly for her guitarist-singer-lyricist beau.

When Whibley was spotted wearing a silver band on his left ring finger earlier this year, he shot down rumors that the pair had already tied the knot, telling Teen People, "I've been practicing (playing guitar) with it. … It's fun to mess with the press."

The bride has been especially busy these past few months. Besides preparing for the wedding and giving voice to a

 possum in the animated film Over the Hedge, Lavigne has a third album in the works. (Her first two albums were 2002's Grammy-nominated Let Go and 2004's Under My Skin.)

Of her new album, she told PEOPLE in May, "there's going to be some love songs on there. That's what I feel, so that's what I'm going to end up writing."