>I am sure this should be simple since the entire purpose of iExplorer is to be able copying files from PC to iPad. But I can't get it. When I open iExplorer and navigate to a "folder" on iPad how do I command to copy a file there? I don't see a Paste button. I must be missing something simple. If you use iExplorer and done copying files, please let me know how.

IIRC, the ipad is a closed system. The only way to get files on there is through the apple store.