forms for invoices and quotations

1

How do I add a new form for invoices and quotations?

2

You cannot. You use the existing forms. See, for example, these Guides:

https://www.manager.io/guides/7178
https://www.manager.io/guides/7238

Almost every question you have is answered in the Guides. Also, as a new forum member, please read the rules of the forum: FAQ - Manager Forum.