C# UWP download files from Web [duplicate]

This question already has an answer here:

• Download and save a picture from a url Universal windows app 2 answers

i want to download files from web.

Situation:

I had a Link:

https://servername/app there are many Subsites with Images like:

https://servername/app/111-111-111.jpg

https://servername/app/222-222-222.jpg

https://servername/app/333-333-333.jpg

I Need to download the requested pictures.

i tried the BackgroundDownloader Class, but that aint works for me.

BackgroundDownloader Class

Questions:

1. Normaly i dont have the direct Link to the Picture. So it is possible to get a list with all subsites from this page https://servername/app ?

2. If i got the Link like https://servername/app/111-111-111.jpg , how can i save this pictrue in the Pictures Folder?

Edit

It could not be a duplicate because of my first Question, thanks.

It would be awesome if someone can help me!