Jung's writings are contained in The Collected Works of Carl G. Jung.
I have to warn you that most of his works are not easy going, but they
are full of interesting things that make them worth the trouble.
If you are looking for something a little easier, you
might try Analytic Psychology: Its Theory and Practice, which is
a collection of lectures and is available in paperback. Or read Man
and His Symbols, which is available in several editions ranging from
large ones with many color pictures to an inexpensive paperback. If you
want a smattering of Jung, try a collection of his writings, such as Modern
Library's The Basic Writings of C. C. Jung. The best book I've
ever read about Jung, however, is the autobiographical Memories, Dreams,
Reflections, written with his student Aniela Jaffé. It makes a good
introduction, assuming you've read something like the preceding chapter