I want to tell my parents I need therapy. how do I tell them, I am scared.

Firstly, it is great that you have realized on your own that you may need some external help.  Many people stay in denial because therapy is either viewed as a luxury or unnecessary due to culture, religion, social economic class, or color. But honestly, as a person of color and religion that practices providing therapy, it is for everyone, for everything. I am not sure why you find yourself wanting or needing therapy but it can be used for all kinds of things. People seek therapy to help with the typical anxiety or depression symptoms but also to help brainstorm coping techniques or activities and skills.  

Depending on your age and relationship with your family or parents, you can of course simply start off by having a conversation with them about their own mental health. Pick their brains about their philosophies about going to therapy and how they contend with the hardships of life or extended periods of life when they feel misguided.  And if they have ever been or have considered therapy or life coaching at all. Then present them with a hypothetical scenario where they are offered the opportunity to get therapy, counseling, or life coaching themselves and see how they would react. You can even go a step further and ask how they would feel about someone they knew and loved going to seek help. If those questions are not received well, then I would pursue other options as you will likely not receive the support you are needing to enter counseling from them. If they do have a neutral or favorable answer to those questions, I would use that as my opening to have the conversation, generally, about how you have been feeling or what you have been experiencing and that you believe it simply just want to pursue counseling to deal with some things. 

If you are either not comfortable with talking to them at all or things simply do not go well with those questions,  there are low cost options like Open Path Collective, that will allow you to pursue counseling or therapy for a low as thirty dollars a month after the one time fee. If you are still a minor in school, your school should be able to provide some guidance on low cost or no cost options for you especially since you are likely over the age of 12 and can consent to treatment on your own. There is also a website called 7cupsoftea (7 cups of tea), where you have volunteers, both mental health and non, that will provide a counseling like environment where you will at least feel heard and be seen. 

I hope this helps and wish you luck.