What file do u save a video to put on youtube?

it says that it's in the wrong format to put on youtube.

i save my videos in WMV using windows movie maker

you can use windows movie maker to get your video accepted on youtube, if you did that then you probably left it in a MSWMM format which is only the project file not the movie file, this would give you the wrong file format message as youtube does not recognize it
follow these simple steps to convert your video and then get it up and running on youtube:

-open windows movie maker
-press 'import audio/video
-import the video you tried to upload
-drag it to the time line
-edit it (optional)
-press PUBLISH MOVIE (at the top of the screen in the middle) or if you have an older version of movie maker then press the file tab and then SAVE MOVIE AS (not save project as)
-press PUBLISH TO THIS COMPUTER/SAVE MOVIE AS
-name it
-save it

it will now convert to a WMV format and will save to your video folder
once it has completed do the following:

-go to youtube
-sign in
-press upload (in the top right hand corner of the home page)
-fill in the video information
-upload the video
-wait on that screen until it says your upload was successful and can be viewed shortly after it has finished processing

NOTE: it can take up to 6 hours to get a channel icon from your video and it can take up to 72 hours before your video will return in the searches but it can be viewed from your profile as soon as it has finished processing

-Jake

Yep, just like Jake says.