you have to with itunes, below is the steps on transfering movies to iPad :
Step 1: Connect iPad to Computer and open iTunes. If you don’t install iTunes, please download iTunes ( apple.com/itunes/download/ ) here.
Step 2: Click “File - > Add File to Library…” or “File - > Add Folder to Library…” to load videos into iTunes library. Then the imported video files will be displayed in Movies section.
Step 3: Choose videos in Movies section, and drag/drop them to iPad icon. And then iTunes will transfer videos under your iPad movies section directly. Once the sync process is done, you can click “Movies” to check those transferred videos.