I would highly recommend against self medicating.
Firstly if you have symptoms which you think indicate a low testosterone (whatever they may be), it could in fact be a symptom of something dangerous that you really should get checked out.
Secondly, human hormones are a carefully balanced system. An experienced doctor will be able to provide medication which they can monitor through regular testing. If you self medicate not only have you no experience, but you cannot get accurate blood tests, meaning you're flying blind. A quick read online indicates that testosterone supplements may have rather unflattering effects on your genitals. Are you sure you want to risk it?