Those with no experience with pre-OS X Macs will want to start with the online options or with Mini vMac. Using at least System 7.1 with Basilisk II or Sheepshaver makes sense, and for all intents and purposes this requires a new large HFS-formatted (not HFS+) disk image, which is non-trivial to create these days (see FuseHFS below). Freely available floppy images are more than sufficient for Mini vMac.
If any terms here are unfamiliar to you, start with Mini vMac or PCE.js. They're very easy to use and work well.
Emaculation is a site that may be very helpful to you
Many useful disk images, including MacPaint 1.5
Download System 6.0.x, 7.0.1 or 7.5.3 from Apple legally
Users of OS X 10.6 or higher will need FuseHFS to write to HFS standard volumes (disk images). That link points to my build of FuseHFS, which should work on 10.6 through 10.9 with OSXFUSE, but there's also the original version that requires MacFUSE and doesn't work on 10.9.
NOTE: despite them not being available for sale for over a decade, it is illegal to copy and distribute old Mac ROMs, which are required to run most emulators other than vMac or PCE.js. If you're going to do this, make sure to rationalize it somehow. Some of the Apple OSes you may want to use are also not freely available from them, so do be careful and ethical online.