Install Jenkins.
Pre-Requisites:

Java (JDK)
Run the below commands to install Java and Jenkins
Install Java

sudo apt update
sudo apt install openjdk-11-jre
Verify Java is Installed

java -version
Now, you can proceed with installing Jenkins

curl -fsSL https://pkg.jenkins.io/debian/jenkins.io-2023.key | sudo tee \
  /usr/share/keyrings/jenkins-keyring.asc > /dev/null
echo deb [signed-by=/usr/share/keyrings/jenkins-keyring.asc] \
  https://pkg.jenkins.io/debian binary/ | sudo tee \
  /etc/apt/sources.list.d/jenkins.list > /dev/null
sudo apt-get update
sudo apt-get install jenkins
**Note: ** By default, Jenkins will not be accessible to the external world due to the inbound traffic restriction by AWS. Open port 8080 in the inbound traffic rules as show below.

EC2 > Instances > Click on
In the bottom tabs -> Click on Security
Security groups
Add inbound traffic rules as shown in the image (you can just allow TCP 8080 as well, in my case, I allowed All traffic).