How to send attachments through ZOHO?

I have zoho as my default for most email functions but I send a fair amount of files as attachments.
Since I have Thunderbird as my client that automatically takes the file and sends it through that.

Well I want to get rid of T-bird so how do I send files through ZOHO without jumping through too many hoops to do so/

AND would ZOHO be the default for everything if I didn't have an onboard client at all>

thanks.
Brad.