Niamh.

There can be many issues:

• could there be a problem with your provider ?
• Mayba a firewall that's interferring?(disable them during upload)
• Is there enough space at your webhost?
• Set passive of (or if off try on)

You could try to export your project to HDD (step 5) and then upload to your host with Fillezilla -> download free from internet, this program can upload websites to webproviderss this helps sometimes...