Check out some of Atlassian's Documentation on setting up a CI/CD server as a good primer. Specifically the guides under the Continuous Integration section.
You are going to need to do the following:
Make sure you setup node and any other dependencies on the Bamboo server first
- Setup a Bamboo project that is a "repository" of your different build plans.
- Setup a Bamboo plan that contains the specific "jobs" that are required to build (in this case get the source code and build it.
- Setup a task to checkout source code from Bitbucket.
- Setup a task to build the source code.
Once you have that setup you can then dive into the Continuous Deployment sections of the guides to learn about how to handle generic deployments using Bamboo. You can adapt these steps for your Nexus specific deployment.