Study rooms are only available on a first-come, first-served basis, so there is no way to schedule them in advance. Certain times of day are busier than others, so you are welcome to come into any of the CSN campus library branches and visit the Circulation desk to request a room. They can let you know if there are rooms available or if there is a wait at that time. You must have a valid CSN library card to use a study room, and they are available for 2 hour use.
If you are not able to wait, there are also public libraries in the city that may allow scheduling rooms in advance, but you would have to check with the individual branches (a list of Las Vegas-Clark County branches can be found here: http://www.lvccld.org/about/locations.cfm and a list of Henderson District branches can be found here: https://www.mypubliclibrary.com/catalog/library/userdef/locations.aspx?ctx=1.1033.0.0.6)