How can I apply my health insurance I'm here in...

If your inquiry is related to work in Abu Dhabi, even though your visa follows Sharjah and has refused health insurance, here is the following information:
You will not be able to obtain health insurance in an emirate that differs from the emirate that issued you a residence visa, so you must submit to health insurance in the emirate of Sharjah, and if the employer refuses to include you in health insurance, you must submit a complaint to the Ministry of Human Resources and Emiratisation