divide VPS

[w-gu2do-0]

I want to divide my VPS (3 TB) into 2 partitions of 1.5 TB. Partition 2 should be used for backup.
The VPS is an empty one.
I am using the fdisk command.
After partitioning and writing to the disk, I am unable to boot my VPS.

I did the following:

# fdisk /dev/sda
Command: d
Partition: 3
Command: n
Partition: 3
First sector: Enter
Last sector: 3075274735
Command: n
Partition: 4
First sector: Enter
Last sector: Enter
Command: w

# reboot

My VPS doesn't boot. It doesn't ask me to login.
In my control panel I reconfigured the VPS and started over again.
The VPS doesn't ask me to login. Via the control panel of the VPS I reconfigured the VPS.

Which command do I have to give after the above mentioned commands?

Kind regards,
Guido