Oh I did that sometime ago with other CMS, is not good, better you learn first and then include your features on your theme or create your own plugins/themes. In the midtime you can use features from plugins on the worpress market.
Anyway I suggest you first follow the FreeCodeCamp Responsive web design path. Javascript basics and learn some PHP basics too (there are a lot of tutorials on youtube). With those knowledges and the wordpress documentation you can create your own themes and plugins: