The command looks something like this:
java -jar agent.jar -jnlpUrl http://10.201.64.144/computer/Agent_Node_1/slave-agent.jnlp -workDir "E:\Jenkins"
You need to execute it after downloading the agent.jar file.
The complete process of launching a slave by connecting to master is given here: https://www.edureka.co/community/48364/windows-slave-agent-jnlp-have-jenkins-master-configured-linux?show=48364#q48364
Hope this helps.