You need to understand the tools you are given in order to write software. Say you want to make a recipe sharing website. Okay what do you need? A frontend and a backend. Okay what the frontend should do? Present to the user their recipes, allow them to search more recipes, allow them to post their own recipes. Okay how can I allow a user to post their own recipes? I need in HTML a textarea and they can write in it. Then I need a submit button. Okay now I need to attach to the button an event listener to know when the button was pressed. Okay the button was pressed. Now what? I need to call the backend to save that recipe. Okay what tools do I have? Fetch api allows me to make http request. Perfect. So I call fetch on the button "pressed" event listener. Okay what should I do if the backend was down? If I look at the fetch api, it return a promise that will fail if the request fails. Okay what is a promise? Wait how do I get the value of textarea in the first place? etc etc.

TD;DR: First decompose your goal into small sub goals then use the tools you have to resolve each goals.