Greasy Fork

how to install?

tried many things but i don't understand it.

If what you mean is "how to install this script"
Try

1). Install Userscript manager extension for chrome
(try tampermonkey extension)
https://chrome.google.com/webstore/detail/tampermonkey/dhdgffkkebhmkfjojejmpbldmpobfkfo
(alternatively, you can try violentmonkey)
https://chrome.google.com/webstore/detail/violentmonkey/jinjaccalgkegednnccohejagnlnfdag

2). Go to this script page
https://greasyfork.org/en/scripts/30964-kissanime-auto-captcha-v3
and click "Install this script"

3). other tab will open, just click install.