To update your nameservers at NameCheap and have your domain point to Skystra, please follow the below steps.
1. Login to your NameCheap account.
2. In the left frame, select the Domain List option.
3. Find the domain name and click the Manage button on the right side.
4. Locate the Nameservers section, and select the Custom DNS option from the drop-down menu.
5. Input following nameservers into the appropriate fields:
6. Click the green checkmark on the right side to save the changes.
It can take up to 24 hours for the DNS changes to propagate (DNS propagation is the process of updating every server across the internet with new information) globally.
You can use whatsmydns to track the progress of the DNS propagation for your domain.