"those smell horrible"
If you are playing with any kind of spray then you know outside works best right? At least in cases where you don't have proper breathing gear (you don't).
Anyway painting plastics can be a right pain. There are also an awful lot of different plastics and some of those have different requirements. Now realistically the monitor shell is going to be HDPE, ABS or maybe once in a blue moon it will be PMMA. If it was a VGA one then polystyrene (PS) is an option but I would be quite shocked to see that in a standard LCD today.
I should also mention that stickers/vinyls exist for a reason and could be the far better option for you. Also an option is building a case of some form -- far easier to paint a wooden box after all.
In either case you will want to remove the bezel (don't try masking, it will not do well in this instance) and avoid blocking any ventilation ports (no point in making a nice mod like this to have it die in 5 months because it cooked itself).
The finish of the plastic is also important to consider -- if this is some piece of apple junk then they often have the shiniest of the shiny finishes that attract all the fingerprints, now consider what happens when instead of your oily fingerprint it is an oil based paint. A nice matte one on the other hand.
First I you should use a spray but not a car one lmao
There are somes specifically intended for plastic
Just google it and search for spray painting tutorial
What do you think many car bodies and interior trim are made from? I will give that cheap cans are probably intended for basic steel, especially if the OP is in Argentina, but I would look at car stuff as part of this.
Also for as useless as computing, electronics... tutorials are then painting is just as bad. There is some good stuff but without the grounding needed to sort the wheat from the chaff of the tutorials