I would like to read books in Welsh. Are there such sites? Thanks for the help.
Amazon.co.uk sells Welsh novels, many aimed specifically at adult learners with a glossary of new terms at the bottom of the pages.
I would recommend "Ffenestri" by Lois Arnold. It's a collection of short stories and poems that start of at mynediad level and progress through sylfaen to canolradd level. There's something learners of any ability should find accessible.
I've just started reading "Bywyd Blodwen Jones" by Bethan Gwanas. That's very good but a little harder for absolute beginners than Ffenestri. It's also in a more Northern dialect, whereas Duo tends towards Southern more. I'm not finding that much of a problem though.
Gomer Press (https://www.gomer.co.uk/) publish and sell many books in Welsh (including both I mentioned above), aimed both at learners and first-language speakers and they ship both to the UK and worldwide.
Yottskry speaks good sense. I have used/am using some of the afore mentioned. "Ffenestri" really is good and fun too. There is also a good mag called "Lingo Newydd" which comes out 4 times a year and has easy/more difficult sections.
I also use children's books from time to time.
There is a Welsh publisher called "Y lolfa" look them up as they do books and different levels.
I don't know where you live but if you live near Cardiff there are several Welsh Language bookshops there and they can advise too.
Start with easier books, if you are a beginner, don't try and do hard books or you will get discouraged.
Use the internet and YouTube too. If you can get S4C (the Welsh language TV station) you won't understand everything but it will help you cue into normal language speed - you can always put on the subtitles too.
Have a couple of lingots to encourage you.
Thank you very much for the valuable advice and good wishes. Of course, I will start with children's books, I am just starting to learn Welsh. I live in Russia and only publications on the Internet are available to me. But S4C I can partially watch.
I sometimes listen to BBC Radio Cymru. As yet I don't understand it, but it gives you the sound of the language and it's fun spotting words you recognise and making sure you remember the meaning. It's interesting how some speakers slip English words into the conversation - I noticed the same phenomenon with Hindi/English in a Bollywood film.
There are a number of books written especially for adult Welsh learners. An older series was Ar Ben Ffordd (https://www.ylolfa.com/products/9781847716774/pecyn-cyfres-ar-ben-ffordd) which has two books at each of the levels Mynediad, Sylfaen and Canolradd. This Duolingo course is based on the introductory Mynediad and Sylfaen levels.
A newer series is Cyfres Amdani (https://parallel.cymru/amdani/) which has five books, and perhaps more to come, at each of the four levels Mynediad, Sylfaen, Canolradd and Uwch.
There are many more books also aimed at adult learners.
Also see http://www.gwales.com/home/