Support on the platform is located in the bottom right-hand corner of any screen when you're not logged in.
When logged in, click your profile icon at the top right and scroll until you see Contact Support.
Paperstac Support can help with all the issues with the platform.
If you have note-specific questions, it is best to contact the seller of the note in question.
You can do that from any listing on the site by using either the Message Seller or Make Offer buttons.
The note seller can answer any questions about any given note on the platform.
It is also good to note that just because you're asking questions does not obligate you to any transaction, obligation, etc. - it's just a way to communicate directly with a seller.
To send a message to a seller, you will need an active paperstac account.