Oi, you're making vague questions so you'll get very generic answers. You can find papers which will walk you through the basics of energy harvesting (ie. impedance matching, rectification and it's losses, etc). A lot of them have test circuits they build with discrete components as well you could just copy or you could even buy some of the existing COTS chipsets or their development kits.
All the general information on how to do this is widely available, if you have a specific problem you'll have to ask a specific question.