How to add music to the videos I make?

How can i edit my videos to add letter and music??

• Okay so you know how on youtube they have their own videos with their own music and letters. Also to cut out like a certain piece from the video. Or just put together different clips. and how they make like .... videos, or slideshows whatever you wanna call them, they are pictures and they add music and letters. well anyways i want to know how to do that. So Can someone help me and tell me how you do it?? plz. Well thank you so much to the ones that do help.

• Answer:

  windows movie maker. search for it on your computer if its not a mac. if it is a mac, im sure they have apple movie maker ;) (its free)