App for displaying pictures to like
I'm not sure what this program is trying to do, but I can give a few suggestions for style and improvements. 


Firstly, unless you're not using the python command to run this script on the command line, you don't need the #!/usr/bin/python. 
Secondly, I'd separate the imports out on each separate line like so.




import cgi
import cgitb
import json





This is in case an error occurs with the imports, if thats the case, the error will be easier to find. 
After that I'd separate certain things into functions and add docstrings. A few things I might want to separate into functions is opening the file, updating the like values, and writing to the JSON file. This gives your program a bit of re-usability. 
My final bit of advice would be to remove or improve un-needed comments such as the following.




# Create instance of FieldStorage
# Open a file
# Import modules for CGI handling




I'd also recommend checking out Python's style guide, PEP8. Hope this helps!