Dear Omar Gomez,
The exact answer to your inquiry depends on your date of discharge, since veterans that discharged in the latter-portion of the 1990s may have to contact their service branch directly. However, this is the best place to start:
Just scroll down to the "Looking for Records" section and click "Start Online Request."
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RRPO (The National Archives at St. Louis). We apologize for this inconvenience and appreciate your understanding and patience.
We hope this is helpful. Best of luck with your research!