All you can do at home without any physical consultation is application of hot pack.
Hot pack on neck region and both upper shoulder region- 15-20 mins for about 3-4 times a day.
Next Steps
Notice your pain for about 1-2 days, if no relief. Visit any physiotherapy clinic nearby you, get properly assessed and treated.
Health Tips
If you have sitting occupational do try to maintain the height of your desk.
Get quality sleep with a good pillow support.
Prevent any exercises suggested by any youtube video or someone who doesn't have the knowledge about this subject.