Search Schedule C and use the Jump to link to be taken to your Self-Employment/Business Summary. Then click Edit or use the pencil icon next to your business to make changes. Then, depending on your platform:
TurboTax Desktop - scroll down to Business Assets and select Start to enter your depreciable assets.
TurboTax Online - Click on Add more expenses, then select Assets, scroll down and click Continue. That will add the Asset entry screen to your business profile.