Welcome to the forum!
I've never tried to create a link in an SVG file before. I wonder if it would have to be actually on a webpage for the link to work? Or well not a webpage, but at least the SVG opened in a browser. Inkscape does not call up the browser, as far as I know.
Just looking at the dialog, there are several fields there, and some of them sound pretty important (particularly "Actuate"). I guess I can only refer you to the manual for this. I have not seen any tutorials.
http://tavmjong.free.fr/INKSCAPE/MANUAL/html/Web-Links.htmlHhm, and I see immediately that I'm wrong, and the manual says that only the Href needs to be filled out. But I'm still pretty sure you'd need to be viewing the SVG in a browser, before the link actually works.
Let's see if attaching an SVG would make a quick test.....
Cross fingers, click on the yellow button.
Edit
Nope, didn't work....probably because of how the forum handles attachments. Maybe inserted into the message?? Let's see....
I guess not
There must be something about the forum software that prevents it from working. Not sure how motivated I would be to either put it on a webpage, or make a webpage for it. I wouldn't be surprised if the forum software doesn't completely support SVG. Unfortunately, it's not unusual - our gallery software needs a special plugin to handle SVG, and no one in that open source community is interested in making it.
But I digress. Maybe I'll try to put it on a test page later.... Let us know if how it goes for you