To add your measurements, you can go to tracker > weight tracker. Once on the weigh-in screen, you can select add measurements.
You can then enter these measurements and save.
If you need to view measurements, you can go to tracker > weight tracker > your diagrams will be below your stats.
Alternatively you can scroll down to log, and click on each individual weigh-in to see the exact measurements entered. Then you can click on the weigh-in date these were uploaded to.