Thank the reply. Thank Chiron! and Thank everone!
>Are you technically inclined? 

I am one of the linux user, and I now using Fedora linux. and I have used Ubuntu linux at past.
So I know how to use linux a little.

But I'm not a programmer,so I cannot read and write the source code.
But I can translate to language (= natural language , not machine languages), I can translation English to Japanese.

And I know how to use PO-file and PO-editor a little.

And I am one of the Japanese Wikipedia and Wikibook editors , and I am one of the Wikimedia's user (Wikimedia is Wiki's media uploader ,for example uploading the illustraiton - including the SVG illustration ),
so I have already post some SVG illustration to Wikimedia, so I know how to use inkscape such as one of the inkscape's users.
Do you  wonder why sujiniku wants to translate the inkscape web page.
Because while my browsing
the website of Inkscape, some part of the Japanese version is untranslated ,
For example , Japanese version of the download page  is many English.

https://inkscape.org/ja/download/

So I want to translate the untranslated sentences to Japanese.

> You can practice on the sandbox page: https://inkscape.org/en/sandbox/
Thanks to your kindness of introduce. But, sorry, I have not editing-rights yet therefore I can not try the test at sandbox.
But I have the some analogy a little , because I have used the Wikipedia,  for example, Inkscape website's "Heading 1" is probably got to correspond to the  Wikipedia's "Header 1"  ?