You can help the development in a lot of ways:
Reporting bugs: via the Forum or writing to our contact form.
Suggesting ideas for the new release (look above)
Translating in your language site, blog, forum, wiki etc. (look above and use this Wiki)
Creating wallpaper, icons set, Mate Theme etc. (same as above)
Working at the new Piumalinux-Repo
Spreading and publicizing Piumalinux!