Couple of things wrong here:
1) You're trying to plug the Freesat cable into the wrong place.
2) You're confusing the Scart input as a "channel".
To get you up and running quickly, try this. Leave the scart plugged in. Look for this button on your remote control:
http://support.dell.com/support/edocs/monitors/S199wfp/en/UG/graphics/icon-1.gif
Or it might be labelled "Source". Make sure your Freesat box is on. Find that button on your remote. Then keep pressing it until you see the picture from your Freesat box.
Post the model number of your TV here and we'll see if we can get things working properly after that ...