The angular momentum of a system of charges $q_i$ located at positions $\mathbf r_i$ is defined as the vector $$\mathbf d=\sum_i q_i\mathbf r_i.$$ If you have a single charge $q$ at $\mathbf r=d\hat{\mathbf e}$ then $\mathbf{d}$ has magnitude $qd$ and points along the unit vector $\hat{\mathbf e}$. Usually, however, this is introduced for two charges of equal but opposite charge $q$ and $-q$. In this case $\mathbf{ d}$ has magnitude $qd$, where $d$ is the charges' relative separation, and points from the $-$ charge to the $+$ one. If there are more charges you need to apply the general formula.
It is worth mentioning that for a neutral system the dipole moment is independent of the origin, but for a charged system it does matter where the origin is (and at the "center of charge" it is zero). See e.g. this question.