If it's general, technical analytical skills you want to develop, there are lots of sites that have free learning resources like Khan Academy: www.khanacademy.org/.../measurement-and-data-g
You don't need to be a mathematician to do good HR analytics though, it's more about what you and your colleagues can do with the analysis than the numbers.
I guess it all depends on what is your current knowledge level. Are you new to the area or currently building complex predictive models or something inbetween?
There are lots of formal training courses but if you have LinkedIn Premium then there are various data courses available and YouTube has a huge range of information.
