Hi @Admin!
I have a valid SSL from Comodo and I don’t know how to install it here in our server. Please help 
Getting an SSL certificate for a domain is a three step process.
The first step is to generate the private key and CSR of your certificate. If the certificate has already been issued, you can skip this step. If you haven’t done that yet, you can easily do it through your control panel. Login to your account and go to the SSL/TLS Manager and select your domain from the list. Next, click the Generate Key / CSR button. Fill in the form on the next page and if everything went right, after clicking the Generate Key button the first two fields in the table are filled in.
The second step is to get the certificate signed by Comodo. To do this, you will need to purchase a certificate for the specified domain. Then, you can try to Issue the certificate. To do this, you will need to send the CSR you just generated (second column in the table) and send it to the place where you purchased the certificate. In this part, the exact steps differ per provider so I can’t give detailed steps here. Anyway, after this step is completed, you will receive an e-mail from Comodo with your certificate files.
The third and final step is to install the certificate on your account. Go back to the SSL/TLS Manager for your domain. In the ZIP you have received, you will find more ZIP files containing the certificate in different formats for different web servers. To install the certificate at InfinityFree, use the NGINX zip. This zip will contain one text file. You need to copy the contents of this text file to the third box on the SSL/TLS Manager called Certificate and click the Upload Certificate button after that.
Once you have completed these steps, you have installed the certificate on your account. Note that it can take up to 15 minutes for the changes to be applied to your account and that some browsers store certificates for some time so you may need to use a Private Browsing mode to test the certificate installation.