The librie has two rows of buttons, one along the left side and one along the bottom. If you don't have your own Librie yet, you can see a hires (1518x2330, 1.1MB jpeg) image of the Librie at:

Down the left side:
| ページ | Page – forward and back |
| 文字サイズ | etter size, zoom 100%, 125%, 150%, 175%, 200% |
| 入力モード | Input mode – hiragana or roman letter |
| 変換 | Convert/Enter |
| 登録 | record/save |
Across the bottom:
| 本棚 | bookshelf |
| 辞書 | dictionary |
| メニュー | menu |
| ページ | previous page |
| 押 決定 | scroll wheel: push to select |
| ページ | next page |
| 戻る | back |
| 決定 | select |
Above the letter X on the keyboard, it says 小文字、which makes certain hiragana letters small when you're inputting in hiragana.
The word above the last blank key is ジャンプ (jump), which I think lets you highlight a kanji character and jump to its reading – very handy for students of Japanese!
The sliding button on the bottom right says:
電源 切 入/スタンバイ (Power On Off/Standby)