From the main menu select Settings -> Document types -> Add. Fill in the fields as shown in the image below for the shipping note or change the title accordingly for a proforma invoice.
If you wish you can choose it to be a default document type when you create an "estimate" or not. After you click Save, the shipping note/proforma invoice will be available whenever you visit the Estimates menu and press Add. You can also, utilize the Estimates' invoicing functionality, so you can convert a Shipping note/Proforma invoice into an Invoice with just one click!
By pressing the "Generate invoice" button found in each shipping note, Elorus automatically creates the respective sales document, according to the default document type you have chosen for the sales documents (Invoice, Receipt etc). The sales document will be then found inside the "Manage invoices" page to edit or send via email.