Hi Richard,
I can understand the “10” value being printed as a colon “:” character. Check the ASCII table out, and you’ll see ! http://www.asciitable.com/ I was trying to assist your learning in one way but didn’t really focus on the end result (a generic string to the display) which is why I didn’t point you to that solution first. Here’s a couple of related tips:
Debug.Print("My value is = " + MyVar.ToString());
// will show the string in the debugging window of Visual Studio - one of the best features of netmf
String myString = "Value: " + MyVar.ToString();
// can then be used to output to display and to debug output if you like!
Debug.Print(myString);
char_Display.PrintString(myString);
To understand pins, there are usually pin mappings (enumerations) that GHI provide. And Visual Studio can help too. But for the best help, we’d need to know whether you created a Gadgeteer project or a regular netmf Console project - but assuming Gadgeteer (since that’s what the ProgramStarted() in your earlier code implies), here’s how I’d do it for a Cerb Bee Gadgeteer project.
By default, you get an inclusion of the “GHIElectronics.Gadgeteer.FEZCerbuinoBee” reference, and you need to add “GHI.Hardware.FEZCerb” manually. Then, make sure you add a “USING” statement to your program for the new reference (and Microsoft.Spot.Hardware) you can then start typing your command and have VS help along the way… I’ll list what I’d press as I type in <> brackets
outp myLED=n(()pi.
at that point you can see the enumerations of the pins from the generic Fez Cerb - pick what one you want, and you’re good to go !
Be warned, the OutputPort approach we just went through is NOT a Gadgeteer method nor is it Gadgeteer “safe” to share with modules if you wanted to use some of the pins that are not used by a module plugged into a socket. We’re just keeping you moving here, right, not teaching you everything at once? 
Analog input is pretty much the same as the OutputPort example. Let VS help you, so start
analomyAnalog=n(.
… and then you can see the AnalogIn channel enumerations. Here’s where it’s tricky. You need to match the Analog Channel to the individual pin you want. https://www.ghielectronics.com/docs/46/cerb-family describes the mapping for you that should help.
hope this all helps !