Am I about to electrocute myself?

The green one is ground. If you don't hook it up, the fixture is no more or less dangerous than it was previously. If there is no ground wire available, I would just connect the green wire to the body of the fixture work box in the ceiling.

You should connect the green to a ground source if available.

if youre not sure have someone with more experience do it

Green is the GROUND wire, a 'safety' wire ....................

  Before proceeding, verify that the light switch is in the OFF position, and cover it with tape.  If the socket is activated with 3-way switches, you must use a voltmeter or AC tester such as https://www.homedepot.com/p/Commercial-Electric-Non-contact-Tester-with-Screw-driver-NCS-8904R/206177753

If the tester indicates power on the red wire, toggle the other switch.  Tape this switch as well.

The red wire, the live wire carrying AC voltage, must be connected to the socket's center conductor (sometimes called the "hot button"), which contacts the tip on the base of the bulb.  The white wire, which is the utility's neutral, connects to the other terminal.  So, simply connect red to red and white to white.

In the outlet box you should see two bare copper wires connected with a "marrette" (a twist-on connector sometimes called a "wire nut").  One wire comes from the incoming cable, and the other is anchored with a screw to the outlet box.  Remove the marrette and straighten the wire ends a bit, add the end of the green wire to the pair, and replace the marrette to join the three..

thats highly not recommended so i wouldnt do that if i was you

I think you'll be fine

The light would work just fine if you connected just the red and white wires, you know, just like the old light fixture. The red wire is the hot wire that is switched by the light switch. If the red wire somehow came in contact with the metal housing of the light fixture then the housing would become electrified. Normally, there is a third green or bare wire coming out of the ceiling that connects to the green wire from the fixture. The green wire from the fixture just connects to the metal housing of the fixture. This way, if the red wire did make contact with the metal housing, that would constitute a direct short circuit and cause a fuse to blow or circuit breaker to trip cutting off the electricity and making things safe.

Unfortunately, older houses often don't employ this green grounding wire. In situations like that, you just have to make sure that you keep up with your life insurance payments. But the fixture is up on the ceiling and it's not too likely it would be touched at the same time you are touching something that is grounded, like a wet basement floor or some plumbing pipes. And the light would have to be on since the red wire goes through the switch.

All appliances that have metal cabinets, like refers, washers and dryers, floor buffers, etc., have that third prong on the plug, which is the green wire that connects to the machines metal enclosure. So if the hot wire inside comes in contact with the metal housing the fuse blows or the circuit breaker trips. If your house only has the two slotted outlets then there is no green wire system in use (called grounding system) and again you should make sure you're current on the life insurance. If you can't afford life insurance then I can offer you my thoughts and prayers (before the fact, not after! It just might work....).

But then there are things you can do to make things safe if you only have the older style electrical system with no grounding. You can install GFCI outlets or breakers (ground fault circuit interrupter), but that's a whole other story.

If the fixture mounts to a metal electrical box in the ceiling then the metal box might be grounded with a bare copper wire. You should be able to see it if that's the case. If so then you could connect the green wire from the fixture to the metal box. But chances are, that's not the case.

Green is ground and irrelevant here. You can avoid hooking it up and it still works fine and safe.

The green wire is a ground wire, for safety in the event of an internal short in the fixture. Assuming that you're mounting the fixture to a steel box, you can wrap it around any screw in the box, including the mounting screw for the new fixture. Wrap clockwise, so it gets tighter as you tighten the screw.

(I can't say that it would be OK, but a lot of ceiling fixtures get installed without such a ground connection.)