How to use Winrar:
1. Download Winrar (choose 32bit or 64bit depending on your operative system)
2. Install and follow the instructions.
3. Right click on the folder with the files you want to share and choose "add to archive" [picture]
4. Click "OK". [picture]
5. Wait for the "compression / packing" to finish.
6. When the progress is done a Winrar archive will appear in the folder of your files. [photo]
7. You now have a working archive ready to upload to a file host.

How to upload / share the files at Mediafire:
7. Sign up for a free account at Mediafire
8. Create a new folder, name it whatever you want, access the folder [photo]
9. Click "Upload to this folder" [photo]
10. A popup window will appear click "Click here to upload" [photo]
11. Look for the Winrar archive you created and double click on it. [photo]
12. Your file will start uploading, wait for it to finish [photo]
13. When it's done you will get the message "Upload Complete". Click the share link [photo]
14. Copy the link in the box [photo]
15. Use the sharing link in the upload form or send it via e-mail [photo]
16. Done!.

Other guides here:
How do I archive files with Winrar?
Mediafire share tour (Video)