In order to add your current mood or current music to a journal entry, you can use the full mode of the web update client (http://www.livejournal.com/update.bml?mode=full, also accessible by clicking the three dots (...) next to Update in the site menus). The web update client shows fields for Current Mood and Current Music at the bottom of the page.

To enter your current mood, you can select an option from the dropdown list, or you can leave the selection on "None, or other:" and type your mood into the text box provided.

To enter your current music, type it into the text box provided.

Many downloaded clients also support the ability to add this data to your entries. Some clients can even "auto-detect" the music playing in your preferred music player, so that you don't have to type it in. Consult your preferred client's documentation and menu options for details. See http://www.livejournal.com/support/faqbrowse.bml?faqid=158 for more information about how to download a client.

If you would like any moods that you select from the dropdown list to appear with a small icon to accompany them, you can select a mood theme for your journal. Visit http://www.livejournal.com/modify.bml while logged in (http://www.livejournal.com/login.bml) and scroll down to the section labeled "Mood Icons". Here, you can select a theme from the dropdown list. To preview the available themes, click the (preview) link next to the dropdown list, or visit http://www.livejournal.com/moodlist.bml. Select the theme you want to use from the list, and save your changes.

If you type in a mood yourself that corresponds exactly to a mood from the dropdown list, it may display with the correct mood icon. However, not all clients support this functionality.

One of the many benefits of a Paid Account is the ability to create your very own custom mood theme (other benefits are listed at http://www.livejournal.com/support/faqbrowse.bml?faqid=131). Information on custom mood themes can be found in http://www.livejournal.com/support/faqbrowse.bml?faqid=64.