Start by checking out the many vendors you see down both sides of this page. Then keep reading the numerous threads aimed at whatever you have a question about.
You'll find information on cruiser bikes, choppers, road bikes and even trikes.
There are kit builders and the DIY guys who have found ways to use engines from various garden tools, pumps and generators. There are threads (discussions) on the best mounting techniques, troubleshooting and wiring/electrical and much more.
The beauty of our hobby is that you're only limited by your wallet and your imagination. The search feature will provide you with hours of reading. Just type in a keyword/s and sit back and enjoy.
If you have specific questions there's always someone here to help. Good Luck.
Tom