As a start, I suggest learning the following:
Statistics:
\- probability (distributions, basic manipulations)
\- statistical summaries (univariate and bivariate)
\- hypothesis testing / confidence intervals
\- linear regression
Linear Algebra:
\- basic understanding of arranging data in vectors and matrices
\- operators (matrix multiplication, ...)
Calculus:
\- limits
\- basic differentiation and integration (at least of polynomials)
Information Theory (Discrete):
\- entropy, joint entropy, conditional entropy, mutual information