how to import proxy root certificate

I have installed newest dell secure content gateway 5.x vmware appliance (virtual edition).
At proxy settings i can not connet to the internet. Need to import company root certificate to appliance.
how can i do this? i did not see any hint in the docs.
https://dl.dell.com/content/manual49116297-secure-connect-gateway-5-x-virtual-edition-release-notes.pdf?language=en-us

Thanks fo your help.