Below are listed some wonderful programs that promote diversity in the mathematics community. Check them out and see which one is the best fit for you!
Women Do Math
Society for Industrial and Applied Mathematics (SIAM)
Mathematically Gifted & Black
Latinxs and Hispanics in Mathematical Sciences
The Edge Program
SPECTRA: The Association for LGBT Mathematicians
500 Women Scientists
Center for Minorities and People with Disabilities in Information Technology
Mathematical Association of America
OURFA²M²
For an approachable introduction to higher math, check out: http://web.evanchen.cc/napkin.html