Hi @surenaija,
Let's Encrypt does not issues certificates from our web site, but via an API that can be used by software. Therefore, you need to use appropriate software to request the certificate.
In the ideal case, your hosting provider would already have support for Let's Encrypt and allow you to get a certificate automatically (using client software installed and operated by the hosting provider itself). Or if the hosting provider gives you a control panel, ideally the control panel would contain a Let's Encrypt client.
If not, then you can see
for the list of known Let's Encrypt client applications. Most of these are software that are meant to be installed on your web server. If you're not used to installing software on your web server, you might find this process difficult.
A few of these tools are used via a web interface even though that's not provided directly by Let's Encrypt. This replicates something like the experience of using other certificate authorities' web interfaces to request a certificate. A popular example is
which is a third-party web interface to request Let's Encrypt certificates.
The inconvenient thing about using a web interface like this is that Let's Encrypt certificates expire in 90 days, so you'll have to repeat the process frequently. That's why we strongly recommend using software installed on your web server (by your hosting provider or by you), which should be able to request updated certificates automatically when your certificates get near expiry.