How do i get curls like jennette mccurdy?

please tell me how i can get curls like these a href="http://www.jennettemccurdy.com/wp/wp-content/gallery/glamour/Jennette6.jpg." rel="nofollow"http://www.jennettemccurdy.com/wp/wp-con…/a and what styling tool to use. i have fairly straight long hair,but it doesn't hold a curl very well. please help.