Q: Can I upload downloaded music from iTunes into the iCloud to free up space on my iPad? And if so how?

Hi Cathy ...

There are other ways of freeing up storage space >   6 Tips to Free Up Tons of Storage Space on iPad, iPhone, and iPod Touch

To answer your question specifically, you can delete the music from your iPad and then download it again later at no charge - as long as the music is still available in the iTunes Store and as long as the iTunes in the Cloud feature is available where you live.

The way that you delete songs is to swipe across the song from right to left in the songs tab of the music app. That brings up a red delete button. You can also go to Settings>general>Usage>Storage>Music>Edit. You can delete all music on the iPad that way. And if the music is synced to the iPad, you can connect the iPad to your computer, launch iTunes, select the iPad under Devices, click on the music tab, uncheck the Sync Music heading and then click on Apply in the loser right corner to remove the music.

Some helpful reading for you....

Download past purchases

iTunes in the Cloud, iTunes Match, and iTunes Radio availability

FYI, You do not and cannot upload nothing to iCloud. iCloud is for backups. It is not for storage.