There is also NMM (Nexus Mod Mngr) but I prefer MO. Mod Organizer - Stop installing the mods manually and use a mod manager. If you want much more advanced sexual content, rape, companions, BDSM, tons of positions, then you need Sexlab (more on that down below). If you just want naked skins and a simple sex mod, get the Nudity and Physics you want, and then Animated Prostitution.
For Sexlab mods, which this guide is based around, you will need these essential files.