If you're doing this regularly, the easiest way is likely to choose a French keyboard layout in the International preferences pane. (Apple menu > System preferences > International > Input). Note that AppleWorks does not recognize UNICODE character sets, and will crash immediately if you enter text using a UNICODE coded keyboard layout. (All three French language KB layouts are for the Roman character set, so this won't be a problem in this case.)
You might also want to install the French language version of AppleWorks from the install disks that came with your iBook. Click the disclosure triangle beside "AppleWorks Languages" in the applications list, then choose the language version(s) you want installed. Each will be installed in a separate folder.
If you're only creating one or a few short documents in French, you can access the accents form the US keyboard layout using combination keystrokes.
Çç is a single stroke combination, option-c (shift-option-C for the capital)
Accents like `and ´, which can be applied to more than a single character, require two strokes. The first chooses the accent, the second the letter to which it is applied.
option-`, then e produces è
option-e, then e produces é
option-u, then i produces ï
option-i, then o produces ô
option-n, then n produces ñ
Regards,
Barry