Using KeePassC is very straightforward. Let's start in main menu:
There are to things you can do: Opening an existing database (type 'o') or creating a new database (type 'n'). We start with an existing one.
Again you've different choices: Open by file browser (type '1'), open by typing a direct filepath ('2', auto-completion is supported) or open the last succesfully opened database ('3'). To get help in the file browser type 'F1'.
Last thing to do is the choice of the pasword type: A normal password ('1'), a keyfile ('2') or both ('3'). Again, for keyfiles you've the choice to use the file browser or type a direct path.
If succesfully entered the database you can see a window simillar to the image above. Let's start with groups. To create a group type 'g'. You have to enter a group title. It's also possible to create a sub-group by typing 'G'. If a group has sub-groups a '+' stands next to the title. The actual parent group is printed at the top. To enter a new group type 'return' to return to the parent type 'backspace'.
Creating an entry is just as simple as creating a group. Type 'y' and you'll some self-explanatory questions. To interact with your entries type the right arrow and navigate to your specific entry. To copy the password to X's clipboard (if you've installed xsel) type 'c', to copy the username type 'b'. You can open the specified URL in your standard browser type 'o'. To show the password on screen type 'H'.
It's possible to edit all attributes of your entries and to edit the title of a group. Just navigate to the group or entry and type one of the following keys:
To exit the whole program type 'q'. It's also possible to type 'Ctrl-C' or 'Ctrl-D' in any dialog to stop the program. Type 'e' to go back to main menu and type 'L' to lock the database. Saving the database works with 's' or 'S' to save the database to a specific place (again, type 'F1' to get help in file browser). Type 'x' to save the database and finally stop the program. Last thing to mention: Type 'P' to edit the database's password.
Other not mentioned features: It's possible to navigate the whole program with vim-like keys and to parse a filepath of a .kdb-file directly over the command line.