I'm assuming you have Win. XP. If not, let me know. Find the file in your RCT folder and right click on it. Go to 'send to' and then 'compressed folder'. This will zip the file. Make sure you've exported your objects, before you do this...
For download, you have to find somewhere to host it, which is often a difficult task. Ask around and see if you can find someone who will do it for you. I don't know if Ed still has his service, but you may ask him... Once you upload the file, then just post the link.