How do you change and art or bitmap picture into a jpg file?

hey im trying to make a picture slideshow screensaver but every picture i try to get from the net says is a jpg file but when i go to save it , its says i can only save it as an art or bitmap file wtf? i used to make these screensavers all the time but i dont know y it wont work now. i just got a computer from my inlaws (there old one) could it be just the setting on my computer or something???How do you change and art or bitmap picture into a jpg file?
Open the pic in paint and click on file-%26gt; save as-%26gt; then give another name and pull down the menu saying extension and select jpeg.