You can only use IP cameras with a DVR that is intended for use with analogue CCTV cameras IF it is a special 'hybrid' DVR designed to accept IP cameras in addition to analogue cameras.
If so, you would connect the IP cameras to your general LAN.
Issue them with IP addresses within your general LAN's domain range.
Teach the DVR where to find those IP cameras.
Normally there are restrictions stated as to how many and what resolution IP cameras you can add to a hybrid recorder (specific to the DVR model).
For example, the manufacturer may state that you can add 1x up to 5MP IP cameras, or perhaps 2x up to 2MP IP cameras.
Generally, because hybrid recorders are expensive AND limited we do not recommend them.
It is usually better to purchase a new and separate NVR and begin to grow your IP CCTV solution with it.
Thanks for the reply. I might not have to change the plugs. These are the items I purchased off the internet. The seller said it all worked, but I don't have a clue to to wire it up. I'm lost when it comes to network.
Is the NVR the same brand as your IP cameras? If not plug & play is unlikely because most NVRs have a subnet (sometimes referred to as "Internal network card IPv4 address") that they use for directly connected cameras and cameras from the same brand recognise this subnet and should connect/activate straight away, but 3rd-party cameras will use a different subnet and may not connect automatically to the NVRs subnet.
The only way to directly connect 3rd-party cameras to an NVR would be to first connect them to your local network, change their IP addresses (with either the brands own IP utility or a universal IP utility) to match the NVRs subnet range, and then reconnect the cameras to the NVR PoE ports and manually add them with the new subnet addresses, usernames, and passwords.
We usually recommend that for ease of setup and to be able to access all the camera settings you are better off connecting a 3rd-party IP camera to a separate PoE Injector/switch elsewhere on the same network as the NVR and then add the cameras to the NVR over the local network using their dedicated IP addresses.
(One extra thing, the cameras you have are PTZs which may require a higher power input than the PoE ports on your NVR support, to confirm this you would need to check the specs on the camera/NVR product pages and/or datasheets. Most PTZs require PoE+ which supplies up to 30W to the camera, so we would recommend using a PoE+ injector just to be safe.)