If the music CD is in a genre that a young adult audience may enjoy, consider putting posters up at local high schools, community colleges and universities. Before putting up any posters, you may need to check with the information desk or front office, as most institutions have rules about putting up posters. After you've received permission, put up posters in frequently traveled areas such as the cafeteria and bulletin boards by the gym and front doors.
Research local music venues that specialize in the genre of the CD that is being promoted. Though large venues like city convention centers are beneficial, it may be more likely that the target audience will see posters at smaller venues that host local bands. Also consider local bars that host live-music nights, as they too may have a bulletin board for music postings.
If the music CD has a wide target audience, consider putting up posters at local public libraries. Most libraries have community bulletin boards that allow free postings of information and posters. Because many different people may check these library boards, the music CD is sure to be seen by a diverse audience.
Research local coffee shops, as they are usually frequented by a wide audience. Many coffee shops have community bulletin boards where a music CD poster can be placed. Larger coffee shops also sometimes host live-music nights, so check into the type of bands that usually play there. If the bands' music is in a similar genre to the music CD being promoted, the shows' audiences may also enjoy the new CD.