I found to my dismay that I can't attach a file when I am first creating a task. I must wait until the task is created.
While not an onerous task, it did seem inconsistent with the usual ability to do something on Toodledo when you need to something rather than having to (gasp!) plan out multiple steps to get it done.
And, though I know Toodledo's got many improvements on their todledoo list, I will use this as an opportunity to request again the ability to forward an e-mail with an attachment and have that file be saved, linked to the task.