A web app or a web site isn't different from your home.
You want that everything is in order, that you'll find your towel near the sink. Or that your toothbrush don't fall in the water everytime you'll take the soap... You want your guests to find everything they need without asking you. So, that's simply the User Experience design...
The design is all around us.
I find all the little things that they'll make you say.... "Aaaaah is like my home!"...
I hope that your home is comfortable, if not, this metaphor doesn't work.....
The first question is always "What do you know?" but it isn't important with which technologies you carry out your projects.
Today there are many tools available and they do almost always the same thing.
The real question is:
What do you want to do?
If you know what you want to do, I'll study the perfect tool for you.
I always did it.
I have studied and I still study a lot.