how can I run a website same as sslforfree.com to distribute let’s encrypt ssl among other websites
you want to create an online ACME-client?
Then start with your basics:
But that’s not enough. Then you need a complete ACME-client implementation - on your server or something that works in every browser.
That’s a lot of work.
A prior thread with exactly the same question and some detail about this is
In that thread, I described some reasons why this might not be a good idea.
Related: Web browser based ACME clients