1. download tomcat https://tomcat.apache.org/download-90...
2. extract the tomcat and startup.bat:-Windows or .sh;-mac
3. verify if the server is up and running with http://localhost:8080
4. download Jenkins.war file from given URL https://jenkins.io/download/
5. paste Jenkins.war under tomcat webapps folder:- after pasting it automatically create a folder with name Jenkins if tomcat server is running
6. Open up a terminal in the download directory.
7. Run java -jar jenkins.war --httpPort=8080.
8. Browse to http://localhost:8080
9. It Will ask you for initial credentials:- find in below path C:/users/your_username/.Jenkins/secret/adminIntialCreadential
10. While Installing It will ask you which plugin you want to install a select default or select as per need.
11. Jenkins will ask you to set up a new user.