Right click the download link on the darkcoin.io website, pick copy URL/file location or some such.

Switch to ssh/console window connected to your remote machine.

CTRL SHIFT V - poof, correct url. Just punch home "wget " and hit enter. Easy.

If you're using putty, fuck all. I ahve no idea how to help you if you're on a commercial OS, I haven't used one of those for over a decade...

Basically, wget just fetches a url like typing into your browser. If you see it in the address line of your browser, type the same thing... Or copy-paste it however your platform does it. You can sometimes end up with goofy filenames if the server you're getting the file from uses dynamic stuffs... it might save the filename with line options, you'll just have to rename it is all.

I used to awk/grep pages I pulled with wget, such as whatismyip.com's home page, before there were handy dyndns drivers and stuff... It's a handy way to get around pain in the butts like that.