You can attach files via a 'conversation' (used to be called a Private Message). Hover your mouse over the recipient's avatar and select 'message'. (I do not know why it is called a message in one place and a conversation in another...)
Note that Jim Neill's wire diagrams (Papajam - RIP) are copyrighted. He made them as a labor of love and gave them freely to Alfa owners. He always asked that they not be sold/used for profit and not be posted publicly. Attaching it to a conversation meets that requirement.