I assume you want to transfer from computer to your iPad. You can try Apple's built-in app or service, like iTunes or iCloud. If you want to transfer selected items, you can try some 3rd-party apps. Some apps can even work without USB cable, for example, AirMore.
1. Download the app to your iPad and search http://airmore.com/web.html on your computer.
2. Use iPad to scan QR code and click certain button to start choosing files, like "Pictures", "Videos", etc.
3. Tap "Upload" to transfer to your iPad.
If you have media (audio/video files) or apps (purchased through iTunes) then iTunes is the easiest way. Wikihow has a step by step walkthrough on the transfer as well as how to load the media from your computer to iTunes.
If you’re looking to transfer other file types you can use AirDrop for Apple devices, iCloud, DropBox, Google Drive or any other could provider.