If in Windows...
Create a basic world on your server.
Download it.
Delete the "world" file inside the zip you downloaded.
Make sure your world is in a folder named 'world".
Copy and past your "world" file into the .zip file you downloaded.
Confirm the zip file is under 200MB (and I think that might be 200,000- not true 200mb). (this is roughly 36 chunks if your world is square.)
Upload the zip file. Watch the grey progress bar... (for a big world, it's going to start as a couple lines on the left side of the upload box).
Tada!
You don't need to buy/install any archiving tools if you do it this way.
Good Luck!