You have not provided enough informaiton for me to even hazard a guess on how far apart or how many sprinklers you need. The distance depends on your water pressure, pressure drop, type of sprinker head you plan to use and the size and shape of the area to be irrigated. There is a pretty good tutorial at http://www.irrigationtutorials.com/ Take a look at the information and tutorial on that web page first. Once you have read the basics, feel free to post back specific questions.
I just got done re-doing sprinklers this weekend and have had enough trenching for a while. Good luck with the project.