Start by clicking on the gear icon, then press on "Invoice agreements" under "Invoice".
To add a new agreement click on "+ Add", give it a name, choose whether breaks will be used in the agreement or not, add register filters and save.
Each agreement is made of groups of invoice rules that decide which invoice articles your approved time reports are going to be matched with. These rules can be, for example, connected to weekdays, time intervals, tasks, customers, absence or presence just to name a few.
To create a new rule group in your agreement give it a name and click on the blue button "+ Create".
Then add an article to the group by clicking on the green button "+Add". Pick one of the articles in the dropdown menu called "Article", choose it's prio, time filter (standard time, breaks or all) and press "Save".
You can also add a number of other filters: