First Welcome.
Second, you need to do some leg work. Google and Search this forum (a quick google will tell you what a DVR is and what an NVR is). This forum is a powerful tool with a lot of info, but you have to do some work. These types of posts are made all to often and the people here are not simply standing by to generate the same response over and over and over and over.
Third, provide some freaking details. You could have the most high tech IP camera or the biggest POS, we don't know. What do you have, what are you working with, what are you trying to accomplish.
Finally - Use the
tools that are already here and start to educate yourself
Resource Guide on IP Technology for all Noobs
In closing - Welcome again, I'm not trying to be an ass, but a lot of what is asked needs to be addressed by you before anyone here can help.