i like your perspective.
to learn to fish, i suggest you take a look at the
calibre forum, where you can read some questions / explanations other people have posted (and the official calibre faq), and the
epub forum, to learn about the new industry standard format. since you have a 505, if you want to convert your files to a different format, this is the best one. you can also use feedbooks.com to create very high-quality epub files ; if you don't want to publish them, you can put in your text and just request a preview to get the file. in addition, for more general questions about book formatting and creation, there is the
workshop forum.
please don't hesitate to post specific questions ; you will find a lot of very helpful, knowledgeable and friendly people here.
as for calibre, it is designed as a library management tool, with three main functions :
1. organisation of your library using a "logical book" system, meaning you have one database entry for each title, with the appropriate metadata (which you can edit as needed), but under that entry you can have multiple files in different formats ;
2. conversion of files to the format you need ;
3. managing the files on your device by displaying the contents and sending the file to the device, when it is connected.
i hope this helps you get started. have fun with your 505, and learning to fish !