can't install programs in windows 7

I am still new to Mac, but here is my today question. I am running parallels and windows 7 on my Mac. I am wanting to install some windows programs since there is not a mac version. (such as quicken). Whenever I go to install programs using control panel, I get the error message that the disk is write protected and can't be written to. I don't see any option to change the disk. I hope I have explained this well enough someone will know what I am referring to . Thanks.