This is incorrect and misleading right off the bat. Ctrl+Z does not "send process to background." You will almost always need to use the bg command for that after suspending the running program.
I challenge you to read a man page a week. Use that command every day that week. Find away to use it with two or three other commands you know. Breakdown tasks into units the size of commands you know. Fill in missing pieces with bash or scripting language of choice.
don't forget to `man man`, and maybe `info info` too. knowing about man sections can be helpful as well.
Ctrl Z is stop/suspend, unless the application has handling for that signal (e.g. lftp)
Now off to learn about disown, dtatch and nohup
and then looking for a way to send everything via the keyboard brought me to http://superuser.com/questions/288772/shell-sigkill-keybindi...
`jobs` might be useful to you as well, in that case.