Learning pathway to making my own apps?

Lets say I want to make a website like etsy or ebay but a lot different in design and general User Interface?

So far, I learnt html5 and css and some adobe design software, what learning pathway should I take now, according to your experience with full stack development, in order to be able to code and style my own BASIC versions of desktop web apps and mobile apps?

I would prefer a learning pathway that does not involve a lot of mathematics as I am not a math-friendly brain.

From what I understand by googling various sources, I should learn a scripting language like PHP and basic programming concepts? Am I correct or?