Comodo SSL Cert onto a Lightsail Instance of Wordpress

I've migrated my website from A2 Hosting onto a Lightsail instance of Wordpress, pointed my domain from Godaddy and installed a Let's Encrypt SSL cert onto my site. Everything is running fine.

However, I have a Comodo Essential SSL certificate that I would like to replace the Let's Encrypt cert but cannot seem to find any clear step-by-step instructions. Comodo support gave me their list but it's not so clear and mentions Load-Balancing - which I would rather not use due to the pricing.

I would be extremely grateful if anyone has a clear list of instructions on how to deploy the cert without breaking what I've set up so far.

Thanks.