These instructions will help you make a handy bookmarklet so you can send links from Safari to iDownload.
Tap the plus button at the bottom of the screen, then select Add Bookmark.
Save it in your "Bookmarks" folder. Then tap Save.
Tap the Bookmarks button at the bottom of the screen.
Find the bookmark you just saved ("Open with iDownload").
Tap Edit, then tap on the bookmark itself.
The finished URL should look like this:
When you're surfing the web and find some file you want to download, just tap the bookmarks button, then tap "Open with iDownload".