How do I restrict access to my wp-content/uploads directory?

I have a vague understanding of a thing called .htaccess, a hidden text file that sets permissions for directories. But that’s all.(Kinda know what it is.)

I want to limit access to my wp-content/uploads folder and every folder inside of it, so people can’t type in the address of my files and access them or hotlink.

Is this already done for me with wordpress, or do I have to make an .htaccess file? If so, how, and what character encoding?

Please help!