Hi im making a virus scanner and i need to know 2 things, asap.

1. How do i look for files 1 by 1 trough the computer.
Ive already got my ScanFile function, i just need to find all the files on the machine 1 by 1, so i can implament my function as in

ScanFile(File)

2. I need to know if there is any way trough API to figure out what file is being selected while the prog is hidden in the back, and return the path so i can call ScanFile(on the file that is selected) to see if it is infected.

Please! Any help would be GREATLY appriciated!