I’m here now so I’ll answer:
You have to go old-skool when coding HTML emails. Many, many tags and CSS properties are unsupported by the various browsers and web based services. My own general rule of thumb is to use table based layouts, standard text (no fancy fonts) over solid colours, and for anything that isn’t standard text, slice it out as an image and drop into a table cell on its own.
There are some really handy support tables online that’ll show you what can and can’t be used, such as this one:
https://www.campaignmonitor.com/css/
Hope this points you in the right direction, but as Rob says, this isn’t the right place if you need further help.