Reducing sedentary lifestyle and physical inactivity is getting an increased attention of researchers and health organizations due to its significant benefits on health. In the same direction we are proposing a virtual community system, TogetherActive, which supports people in their daily physical activity. The community is connected to physical activity sensors and provide social support (informational, emotional, instrumental and appraisal supports). In order to increase motivation, individual and group goals, comparison, competition and cooperation are the key concepts considered in the system. This paper presents the design, implementation and usability evaluation of the TogetherActive system.