IT jobs are usually listed at online job boards, so start your search there and post your resume to be found by employers. Concentrate on the boards from any organization to which you belong. In fact, job boards are one of the nicest benefits of membership in professional organizations. Many organizations have student memberships that are much less expensive than full membership, and you can find an abundance of information about IT jobs, trends in the field, and support from others in the IT field.
Occasionally, you will see an IT job in a newspaper classified ad or be able to attend a job fair that has tech companies present. If you go to a job fair, take copies of your resume and go dressed for an interview.
Check with your school placement office for any job leads. If you are still a student, do what you can to start an internship while you are still in school. Internships often lead to full time employment and if not, the experience you gain shines on a resume.