Erm..it depends on how experienced you are, really. Publishing a website live can be trivial if you’ve done it before, but if this is your first time, it can probably be a bit confusing.
There’s a series of steps that you need to take to publish a website. Generally, this is what you have to do:
1. Subscribe to a web server account and register a domain name
2. Upload all the WordPress files to the server
3. Transfer the WordPress database from your local server to the web server
And yes, it is still possible to edit the website once it’s up.