My neck muscles are tense and i would like to learn stretching exercises.

PT/neck hammock: I would suggest range of motion exercises. massage thery, heat therapy and the use od Neck Hammock ( excellent) . I strongly recommend a medical exam with x-rays of your cervical spine.

Several options: You can schedule a visit with your doc & have the issue evaluated. If no x-rays or other testing is needed s/he can send you to a therapist who can teach you these maneuvers. In the short term you could look on U-tube where many related videos explain/demonstrate the exercises. Any work you do yourself should have a time limit, with a visit if you are getting worse/not better.