You will need to find a captcha solver program, either online service or a windows program.  
 
If you have a captcha solver program, you can run the program with something like the following to decode it:  
 
RunApp('solver.exe your_image >results.txt');
code=ReadFile('results.txt');  
 
If you have a captcha service, you can use something like the following to decode:  
code = UrlData('service_url');