This is for Windows. I dont know how to do this for any other OS.
First make sure you have all your stuff. Pictures, music, videos etc.
Steps
- Open up Windows Movie Maker
- Import all your media stuff
- Setup your entire movie and whatnot
- Publish It in High Def
1. Open Windows Movie Maker
This step is pretty self explanatory. Just run Windows Movie Maker
2. Import all your media stuff
Go to File > Import Media Items. Import all of your video clips, pictures, and music.
3. Setup your entire movie and whatnot
Drag your pictures, video clips, and music onto the timeline at the bottom. Put them in any order you want
4. Publish it in High Def
Now just follow the pictures and text to publish it in High Def.
1
Click This Computer then Click Next

2
Type your name of the video in the textbox. Then select the directory to save your movie at.

3
Check the third circle: More Settings then make sure Windows Media HD for Xbox360 is selected. Then click Publish.

DONE!
You are done making your High Def video. Things you can do with it.
Put it on a DVD and give it to a friend/family
Publish it on youtube
Delete it - not sure why you'd do this one though
And more