Travis CI is configured by a .travis.yml in your repo root, and its conventions are mostly about naming the right keys. You set a language, and each language has a corresponding version key — node_js for JavaScript, python for Python, rvm for Ruby, go for Go, jdk for Java. The versions you list under that key define the build matrix.
The actual work lives in lifecycle sections: before_install prepares the environment, install fetches dependencies, and script runs your build and tests. A failing script step fails the build; the earlier sections are setup. An optional deploy block can publish artifacts on success. Versions should be quoted as strings to avoid YAML parsing surprises, and once the file is committed, Travis builds each push and pull request automatically.