Add an ampersand ( '&' ) after the command:
The shell will execute the program in the background. If you want to bring it back to foreground, type "fg". If you want to send to background a program that is already in the foreground, you first stop it with "ctrl+z" and type "bg".
This is all documented in the bash manual (man bash), press "/" and search "JOB CONTROL".
Note that you will still get messages from that program in the console, if you don't want that you could close its standard output and standard error:
me@localhost:~$skype >&- 2>&-
Here, ">&-" closes standard output and "2>&-" closes standard error. I think there's a way to close both descriptors with one redirection but I don't know the syntax.
Similarly, this is documented in the bash manual in the section "REDIRECTION".