I have a picture of myself. I want to turn my skin color to green (like hulk)

Are there any online photoshop generators where u can do this for free?

I do not have photoshop installed.

https://forums.d2jsp.org/forum.php?f=105

In this section, they will definitely help you. Post a topic there and I'm sure you'll find a few people who will give you advice and details

GIMP 2.0 is a free photoshop alternative that has most of the features you will find in photoshop.
Try to look up a tutorial on how to apply masks in GIMP and use a green color as an overlay for the masked out skin area. Then play with the screen modes and opacity until you are satisfied
There are multiple ways to achieve this but I think this would be the most simple solution to learn quickly.