OvuFriend will start a new cycle for you, as soon as you mark the first day of your menstruation.
To start a new cycle, click on a given day, and in the observation tab in the menses/spotting box select menses (light, medium or heavy). OvuFriend will then start a new cycle for you, and the first day of bleeding will also become the first day of your new cycle.
It may happen that, even though you recorded bleeding on your chart, OvuFriend will not automatically start a new cycle (i.e. according to OvuFriend's analysis, your current bleeding does not indicate menstruation). If, however, you're certain you want to start a new cycle, select "start new cycle" located in Settings/Cycles.