how easy will be created new site on finished network? For example if I have some site, then I just upload these files somewhere?
For a simple static site it’s extremely easy - you just upload the files as you suggest.
Quite a few of us have done this in previous test networks and for some sites it is easy, easier in fact than the traditional web. You can create a site and publish it in a handful of commands and it will exist indefinitely with no need to pay for hosting or to renew the domain…
The site itself can be built using existing web frameworks, so publishing a static site is actually much easier (as JPL says) than in the existing web.
The Svelte framework is particularly suitable because it is lightweight, capable, fast and very easy to learn. The are examples using SvelteJS (now SvelteKit), and other Frameworks with Safe Network on GitHub and the developer forum at https://forum.safedev.org/
Very easy for static websites, for interactive go for responsive frameworks like React, Angular or VueJS.
Also try to remove server calls as much as possible, maybe a lot of your ideas can already securely be done on client side.
Later on maybe those calls can be delegated to a decentralized computational layer on safe or even other networks like ethereum. As long as you make your site code opensource and show these server calls are requesting and posting to decentralized networks you already empower the end user a great deal!
More advanced idea would be to use SafeNetwork to host the front-end files of react project that uses nodejs and can communicate to the web3 ethereum contracts to build a FULLY decentralized DeFi app or DEX. Later on would be great to see Safe Network to have its own computational layer but is not immediately necessary!
You could also store certain data encrypted on the network, then with certain smart contracts only users that got certain permissions are then able to retrieve the decryption key to load the content!
Just rub the lamp and the safe network genie does it all for you. Okay, not quite, but compared to existing web, far far fewer steps