String Positions

Ok, im new at c# and I'm having a problem with the program Im working on right now. Not sure if this is a stupid question or not but please try me.

My situation right now is that I have for example a string="msdwsxdf!";
now, what i want to do is get the positions of each character in that string e.g m=1, s=2, d=3, f=8 etc...

ummm... so how do you do that here? I know that I would be using a for loop statement with this. But I'm not sure on how to get the position of each strings. Help?

thanks in advance