There is two way to deploy war (web archive file) in to tomcat.
Method 1: –
Copying war file directly into tomcat/webapps folder.
While start tomcat this .war files will be extracted.
Method 2: –
Deploying through tomcat manager.
For this you need to username and password for tomcat manager.
.war file will be extracted once it is deployed.
Its good practice to restart server once war file is deployed.