and how can i get it on the web server?
Host providers (which provide services for all public websites) do so through their server because the server is where server side languages are run. You can run client side languages without a server. You can simulate the same exact features a host offers on your own machine. It's known as a local development environment. The basic comprehensive format is also known as OS + AMP
Your OS - Apache - MySql - PHP
You can install these individually and configure them to work together, or there are programs that simply replicate it as one package, which may not be available depending on your OS.
I don't know about Python. Look up how to install a local developement, or if you are on a linux, look up LAMP install tutorial. XAMP is able to be used on all OS, and WAMP is windows exclusive. XAMP however is in fact a program that will manage your server for you, LAMP however is a combination of individual components which make it up.
If you want an easy method to get started go with XAMP, though if you're willing to get into it head on, go with a component based installation such as LAMP or WAMP.
These methods will usually run your websites from a specific development folder, and your url will generally be localhost. This will be the directory for that folder, and you can choose your websites to display by pointing to it's directory.
Browsers won't run Python, you're stuck with JS for that purpose.
Does PHP run in the browser? Or just on the server before the page is sent?
I'd go google for a guide or get spoon fed by youtube videos to get some step-by-step instructions to follow the first time through. That'll probably answer some questions and point you in the right direction for some other questions. @emgo_dev has given you a bunch of key words for your search queries!
If you're on windows, you might want to install virtualbox and create a virtual machine with linux on it. Lots to learn! : D
Of course, getting into linux might be a huge obstacle in terms of things that have to be learned before you can get the results you are looking for, so WAMP might be the way to go at first. Missing out on some of that terminal action though!
My point is that you don't need to jump into a local server environment to really get experimenting what front end web development. Give it a shot if you haven't, set aside a normal folder for a site or project app that runs in the browser, create your structure files, script files, and stylesheets; then open your html file with your browser, or look up how to target your file through the browser url and just point to that directory.
As everyone else endorsed, if you want to commit to a local server environment, you'd be most benefited from using our terms and finding full fledged guides which will surely guide you through fully setting it up. We've all done it.