1) Identify installation location.
2) Identify connectivity requirements (i.e., power, audio, video).
3) Order camera, cabling and mounting hardware.
4) When hardware & materials received perform installation of mounting hardware, camera, mics (if audio required), pull cable back to NVR/DVR as needed.
5) Add camera to NVR/DVR.
There are lots more steps in these high level process items, but since you provided so little information, it is impossible to provide all the steps your particular installation might need.
Since you have to ask, it might be more appropriate for you to hire professional installation.