Answer 1

SoloLearn offers 11 tutorials at the moment. Maybe they will add some in future but this is not the point. The simple reason is, just because you propably want to have a great computer from alienware, they do not send it to you for free.

I do not want to say that SoloLearn will cost something in future. I think that only because you want it, they dont have a reason to implement it for you. It's not that easy as you think to create a good course in a programming language. Be happy about the offered ones.

If you want to start learning C, I think there are tons of books about it and I am pretty sure lots of web sites targetting tutorials in C, so try there to learn C.