chain certificate

hello im try install ssl and get error on chain after check on ssl checker get this message

The certificate is not trusted in all web browsers. You may need to install an Intermediate/chain certificate to link it to a trusted root certificate. Learn more about this error. You can fix this by following Comodo's Certificate Installation Instructions for your server platform (use these instructions for InstantSSL). Pay attention to the parts about Intermediate certificates.

how to fix it thanks.

you need to get chain certificates from your ssl provider and install them