Linux: Send keyboard input to background process

This is a Linux specific doubt.
I start a process, that waits for keyboard input. I press Ctrl+z, and the process halts. Then I write 'bg' in the console and the process keeps running, in the background.
Now I want to send keyboard input to the process but I don't know how. Do I need somehow to give focus to the process, and then the input? Or is there any command line to do so?
Thank you. ;)

Well you use 'fg' to bring the process to the fore, then you can provide input in the regular manner

Example - typing "hello" "world" into cat (just echos back to you) with a pause in between

Code:

---

$ cat
hello
hello

[2]+  Stopped                cat
$ bg
[2]+ cat &

[2]+  Stopped                cat
$ jobs
[1]-  Running                kate &
[2]+  Stopped                cat
$ fg 2
cat
world
world

---

AH! Thank you!