Notepad++

Question

How can I use java, JavaScript, css and python on this software? I don’t want to download anymore software to practice

Answer 1

JavaScript and css - easily. You just run the code, you've written in notepad++ in browser.
Python is almost as easy, but you have to install python on your computer. Then you can make .py files in np++ and run them in the console.
Java is the trickiest one. It is (unlikely to js and python) a compiled language, so, firstly, you have to install java sdk (not just jre) on your computer, then you have to write a .java file (you can do it in notepad++), then compile it, using javac console command and then you can run a compiled file.
Conclusion: yes, you can do that, but there are easiest ways to code. Even for html/css/js you better use a specialised code editor, like sublime or visual studio code, which have more elaborate sintax and error highlighting, autocomplete features, debugging options etc. For java the best for you will be to use some specialized IDE - I'd recommend Eclipse: it'd de facto standard and absolutely free of charge.