I'm losing my mind trying to decipher this old wiring diagram for my CT2. The problems I'm trying to fix are: no power to headlight, left side front blinker doesn't work (bulb confirmed working), front brake light switch doesn't work, and neutral light doesn't come on. 
I'm very new to this sort of thing so I'd love any help or a very easy to read wiring diagram lol.

Welcome from Tennessee 
     Your headlight is a/c powered and your bike has to be running for it to work I would check all your connections in the headlight bucket also do you have a good battery 

Yellow powers the lights-headlight when running. Dark green is left blinker power if switch is working & "battery has power". Same with neutral & brake light switch. Neutral light blue from on top left rear of the trans-say motor is for the neutral switch to earth the bulb in neutral. But bulb 'where ever it is--tacko or speedo--needs a live battery brown operating. Came with front brake switch--live brown battery power. & man i hate wiring diagrams but sometimes we have to go there. All my woffle is from memory of colors & where things go. Everone's here to help so don't be afraid to ask.--& i need correcting sometimes.
Edit to correct myself. Think left blinker is dark brown & right blinker dark green. Opposite to what I said up top.

Have you looked at color code and switch charts that accompanies diagram? You almost don't need a diagram if you know the Yamaha color chart.

Are you in the headlight bucket? Most of the connections you need to check initially are located there.

At the most you need a test light or voltmeter.

If rear left signal is working it must be connected to dark brown (almost black) in headlight bucket. Front left plugs in inside headlight bucket in same place so either FL signal is not plugged in there or there is something wrong with the short wire run to signal or light fixture isn't grounded or fixture is bad.

Front brake light also connects in headlight bucket. Simply follow wires into bucket. One wire that connects to switch is brown which is the common + battery power wire for pretty much everything. The other is yellow/green. It's just an on/off switch so you should have power at brown with key on and then power coming out of switch on yellow/green side with lever pulled.

Neutral light is similar with bulb in gauge powered by a brown as above and other wire is "sky blue" (very light blue) wire to neutral switch on top on trans above shift lever. Power at brown? If yes then ground wire at switch and bulb should come on. Is bulb good?

As was said, engine must be running with key in second "lights on" position to get AC power to headlight circuit.

In addition to the excellent previous replies, have you checked the headlight bulb by connecting it direct to a 6v battery? I ask because they are very often blown, caused by excessive voltage - the cause and correction can be had in a separate conversation! If the bulb is blown and you have to buy a new light, don't try to turn it on until the voltage regulation conversation has been had!

As Mark indicated, the wires fade or darken over time and so it is very easy to get the browns mixed up and the dark greens can look black.

For the indicators, in the headlight bucket there will be triple females for dark brown and dark green. Into these will go the corresponding coloured wires from the indicator switch on the handlebars, the amber indicator warning light from the tacho and the front indicators themselves. Note that the front indicators should earth on the handlebars and the wire coming from each of them should be treated as dark brown/dark green, even if they are actually black.

The front brake light switch might be broken, or have dirty connections in the switch itself. I think that you can test the circuit in the harness by disconnecting the switch and then connecting the green/yellow wire with the brown (to confirm, these are the wires in the headlight from the main harness, not the switch). If the brake light comes on, then the issue is with the switch.

I think that, with care and a little good fortune, the switch can be dismantled, cleaned and then tested - I use a battery and a circuit testing light.

www.slimduck.com/ct2175_wiring.html
Yep dark brown left. Hope link works. Can't find a color diagram but the have to be out there somewhere.

Forgot i have an AT1 manual with a color diagram which should be same as CT2. My book is for a magneto ignition AT1 like your CT2. Not battery ignition electric start. So should be relevant to colors & likely everything. But one thing i never considered is if your tail light in the US is off the battery. I'm in NZ where our tail is with headlight powered from the magneto. Couldn't get my printer scanner to behave so just cell phone pics & a bit blurry.