Manage Jenkins
Install and Configure Jenkins using Jenkins.war if you have not installed Jenkins yet. Once installation is successfully completed with initial configuration, On Jenkins Dashboard, click on Manage Jenkins Click on the Global Tool Configuration Link. Verify Configure System, Configure Global Security, Configure Credentials, System Information, System Logs, Manage Nodes, and so on.

Overview of Jenkins Dashboard

JENKINS_HOME in Windows 10
Go to C:\Users\<UserName>\.jenkins This is a JENKINS_HOME Observe each and every File and Significance of the directories to gain understanding of Jenkins work behind the scene. workspace folder will contain all the source files checkout from the repositories for all builds. jobs folder will contain build wise logs  

Overview of JENKINS_HOME Directory