The copyright registration process, for a simple work, is usually not difficult. There are many forms, however. The most common forms are Form TX for literary works, PA for performing arts, SR for sound recordings and VA for visual arts. These forms may be obtained at the Copyright Office web site, at
http://www.copyright.gov/forms/.
For works that are created from scratch by a single owner, the forms are not difficult to complete. The hardest part is the portion which asks whether the work was created as a "work for hire" (TX Section 2C) or if the work is a derivative work or compilation (TX Section 6). If the work was anything other than a work done completely by the person claiming ownership, experienced legal counsel should be consulted. The issues of "work for hire" and what are derivative works or compilations can be complex and should not be handled without professional advice.
For more questions about copyright or a more detailed explanation of how to fill out the forms, go the Copyright Office's web site located at http://www.copyright.gov/.