The documentation

You'll want to peruse the api documentation.

link to Twitter api document

Making requests

The following is an example of making a read-only request.

// our client
DumbDumbClient client = new DumbDumbClient("client key value", "client secret value");

Map<String, Object> params = new HashMap<String, Object>();
params.put("user_id", "a twitter user id");

// print out the JSON response
System.out.println(client.read("token value", "token secret value", "/1/users/show.json", params));

This project ships with a simple little app you can run to go through the process of getting a request token, authorizing it, and trading it for an access token.

Check out src/test/java/com/blueleftistconstructor/Driver.java . If you run this in Eclipse you'll want to paste the URL it prints to the console into a browser, enable access then paste the verifier value (given from twitter) back in, hit enter and bam.

You can use this simple application to understand how you'd integrate this client into your project.