After Party

This was taken on my cousin's wedding night. She asked me to take pictures for her (I took pictures from morning till night on her wedding day). This is my sister helping the bride's maid to unhook the pins on her hair, it was after the big party. I thought, 'hey this is kinda nice to capture.' I used pocket digicam & the only source of light was the table lamp, which actually made a nice shillouette of my sis But the photo is sooo grainy, I'm not used to take pictures with digicam, anyone know how to prevent this??