How do you set up day/night cycle on sim??

[JettyLuv]

Im sure this has probably been asked and answered many times..but I cant seem to find any answers that make sense or that aren't outdated....
My partner wants to set up a day/night cycle on his sim for shared environment., but neither of us know how and as i said cant seem to find any clear or up to date answers.....so if you can help me with this with some CLEAR directions on how to do it, it would be greatly appreciated!!!
And yes I have looked at what Linden says...and yeah no....
So like I said if you know how  or have experience or whatever and can give CLEAR instructions...i would love it!....thank you!!!

[Rowan Amore]