it's great you want to contribute. Please, don't translate the HTML
files directly. Both HTML (on the web) and SVG tutorials (in Inkscape
help menu) are generated from source .po files - there files are meant
to make keeping translations up-to-date easy.
Here's more info on how to translate inkscape tutorials (check out the
inkscape-docs bzr branch and then send us the translated .po files).
After you're finished, the generated translated HTML files will be
available on the official website and SVG files in the next Inkscape
version in the Help menu.
Good luck and let us know if anything is unclear.