The main difference to understand about Debian and Ubuntu when it comes to installing software is the respository structure naebulys. By default Debian does not come with all of it's repositories enabled. The main ones are main, contrib, non-free, and backports. You said that you were using Debian ten, but I'd recommend using Debian 9 with backports instead. Now that being said, installing repositories on Debian is not as easy as it is on ubuntu. For one, no PPA support except in the case where the ppa is supported by the
add-apt-repository command. Secondly, Debian only comes with it's main repository by default, and you can see this if you type
cat /etc/apt/sources.list. Adding the non-free repository allows you to install non-free software. Contrib holds mostly dependencies of software that is not found in
main. The tor-browser deb repository, for example, has dependencies in
contrib. If you want the non-free repo, use
#add-apt-repository contrib non-free. Backports is a whole other beast and I'd recommend you take a look at this article from the Debian backports website. Yes it has a whole website dedicated to it apart from the main website. I'll offer support for Debian where I can if this doesn't make sense. https://backports.debian.org/ FYI, I do use the Debian backports so I can help; don't be intimidated.
Also, something to note, the reason that I say not to use Debian ten is because that is Debian Testing. It is severely unstable and isn't meant to be used on a main system. You may have a frankenDebian: https://wiki.debian.org/DontBreakDebian . One of the things that even most Linux users hate about Debian is that all of its packages are extremely old (E.g my Debian stable distro uses Kernel 4.09.01 I believe and Ubuntu uses 4.19.0-15). With Debian, you do not need the latest and greatest. But in the case that you want it, that is where backports come in. Sorry that I wrote a paragraph, but I hope this helps. Someone post a TL;DR for this?