Seems to me the best place to start would be their website located here.
Although, after visiting it myself, I wonder. I found links to pages that say they have manuals but there is no actual download. I found that it has feateres instead of features. Maybe try googling by the laptop name might help. I did find a few links by googling for aspire + linpus (I used aspire because I believe Acer is the ones with Linpus preinstalled) and such. But, sadly, if the Linpus website has no downloadable manual, I am not sure you will find one easily.
An interesting short Wikipedia entry.
[EDIT] Go to this site: Nice tutorials and a place to start.
The tagline on his site is "Making Linpus Linux Usable". I think this site would be a great place to start. I googled for linpus + help to find this (and other sites). Google is an amazing tool.
One last place that could help: Aspire One Forums