Step 1: Main Menu.
Calibre is available for most computer platforms. You just have to go to their site and get the verson that is suited for your system. From that menu you can import, read, catalog, and a host of other features. it is so intuitive. you almost do not need a manual.
Step 2: Converting,
The real power of calibre is in converting formats.
Step 3: Chm Files.
Microsoft has a special format for some of it's document files. If you are using linux, you will want to install xchm from your distros repo.
Step 4: You Own Ebooks.
You could use a program like Libreoffice (available for most platforms) and create a file that Calibre can use to be translates to the the format you need. The you can share your self created files with everyone. You could possibly even become rich and famous for doing your own ebooks.