You can create an invoice in three ways.
First, from the main menu,  when you choose Documents and then Add document submenu.



In the opened window choose Invoice.
Fill in the information in the fields, when you choose partner, service/item and etc. , then press Add and Send button.




You will be switched to a new window, where you must fill the recipient's mail. Anyway, if you want to eedit the invoice, you can do it from the actions menu, located right to the invoice.


When you finish filling the information, click Add and Send.
On this way your client/partner will receive an email from you. 

Other way to send an invoice is from the Wizard.


Last option is from the Add button.




After that, the steps are similar to the previous.