Binary data in place of file path while recording

I have an issue related to a Vugen script. the id described as below:

I am supposed to attach a file and upload it in a web application. I have recorded the whole workflow using HTTP/HTML procol in HTML mode. The file to get attached is kept in desktop with a particular name. My script is working fine and file is also getting attached and getting uploaded properly. But the problem is that the web_custom_request which is attaching the file is coming as binary format with the file name hard coaded. So where ever env I execute the script it takes the file even though the file doesnt exist there. The file path is not shown in the script.

My query is:
1. How do I change this binary value in a file path so that I can parameterise the path and file type, so that I can change the file path and type as per the requirement.

2. How can I reduce a file size as well?

I really need the solution ASAP.Please reply me back who ever knows it properly. I will be waiting for any of the exparts' reply.

Thank you.