This is really complicated stuff if you are a beginner.
"the server" - if it's yours...
- does yoour router have port forwarding?
- is your ip staatic?
- what os is your server running?
- php or asp?
- is the server settings using the correct MIME types?
- is it set up to accept "POST" from foreign IP's? (make sure to have security to match the settings)
When that is done you will have to write the code that handles the recieved data as binary and store it in correct format.
Perhaps it would be better to look for alternatives?
If you still wish to proceed, google is your friend.
try:
- "how to set up php server"
- "php save POST to png image".
Please note that nothing of the above is directly related to construct so you will have to get the help from "personal server" forums.
When all that is done, (could take a couple of weeks if you read thoroughly), have a look at the AJAX documentation here:
construct.net/en/make-games/manuals/construct-3/plugin-reference/ajax