When I was born my mother did some bad stuff so they took me and my older brother away and we were sent to live with my father I am 14 atm
And when I was 9 my mother had another child who got taken away and sent to foster care when he was born
And he is 4 now
I need to know if I can fight for custody of him... I want him in my life and ill do anything to make that happen

And I know ill most likely have to be 18 to take it to court but I think its unfair for a sister to not be able to see her little brother because of something my mother did in the past

Can anyone help me with this?

When you are 18, you absolutely can. Start by getting in touch with someone in the juvenile department at your local courthouse and they should be able to point you in the right direction to get started.

It would be helpful to know your current situation. Are you still in your father's custody? Have you been returned to your mom? Is there any court action going on right now about your custody or your brothers?
Is there a reason your dad does not have custody of your brother (do you both have the same dad?)

If your dad is supportive of you, perhaps he can help you navigate and get a court-appointed attorney, sometimes called a "guardian ad litem" to represent your interests as a minor. That person can advocate for what is in your best interests, which can include a continuing relationship with your brother. If your dad is open to taking custody of your brother, perhaps he could petition the court to do so on the basis that it's in both yours and your brother's best interests to be in the same home and family environment, even if he's not your brother's father. It's really complicted and you need a lawyer and an adult like your dad or someone to help you out.

You are right that you are too young to get custody of your brother, but you can try when you are 18.

I have four friends from high school who's mother disappeared - their father was long suspected but had not been convicted of murdering the mom. When the oldest daughter turned 18, she got custody of all of her sisters, with financial help from her mother's family. Their father eventually was convicted. There are cases when adult children are more responsible than their parents, and the court will try to keep the family intact by giving the sibling custody of the younger kids.

You are a wonderful young person to be so concerned for your brother's wellfare. I wish siblings, of all ages, from kidswho are fighting over TV stations and who's turn it is to unload the dishwasher to adults fighting over who was treated better as children or whatever, should understand circumstances like yours and appreciate the chance to simply be together. God bless you.

You can go to Court through a guardian or parent (if you are underage) and request visitation with your brother. It happens.

As far as getting custody - you would need to have finished your education, be self supporting, have your OWN place to live.

Apparently you and your younger brother have different fathers. Is YOUR father interested in requesting custody of the younger brother? He has no "blood line" rights, but he could always try.

And where is your mother in this picture? Is she trying to get custody back?