How do you say 'i speak Japanese' in Japanese?

You spend 5-10 years studying the language (or more, or possibly even less, depending on your skill in language and how long you spend each day studying.)
1. Take a deep breath.

2. Match phonemes in my mind

3. Open my mouth

4. Emit sounds that are accepted as intelligible by other speakers of the Japanese language.

5. Close my mouth.

6. Breath.

---For conversation---

7. Wait for and process an aural response.

(Wash, rinse, repeat.)