Embeds in lilybird are a 1:1 of the discord docs, to put it simple, they are just plain objects with no abstractions or name changes.
To send an embed you just need to pass it to any method that supports it (liked createMessage and createInteractionResponse).
Attachments
Attachments in lilybird work a bit differently from what you might be used to.
Methods that accept attachments will have an extra field usually called files where you pass an array with the files you want to make attachments, the client will auto generate the attachments field for you.
Attachments in Embeds
To have your attachment inside an embed for example as an image, all you need to do is pass the url of your attachment to it