Add a ninterpreter to pycharm

Hello,

I have searched on the internet on how to add an interpreter on pycharm because mine is too old, but the fact is that among the list available I have no choice:

Only python 3.5 interpreter is available in my virtual env.

I try to install new version of python but even I still only have python 3.5 which is not enough to work with API.

If someone has a suggestion.

I run a machine on linux Mint 18 Sarah Mate 64 bit.

Thanks,

Fabien