How to convert Wmv to suitable format for uploading to Youtube and Facebook

[DebbyJune]

After clicking on Convert/Save, and I load the wmv slideshow I made - into VLC upload window, what do I do next? What is the best format to convert it to, for uploading to Facebook or YouTube? What will it look like after conversion? Can it keep the same timing of picture slideshow as in the original? And can I make slideshow pictures to keep their original dimensions the same as in the original one I made? Where do I save it after completing the conversion process? Thanks!