$ convert -delay 100 -loop 0 img1.jpg img2.jpg img3.jpg img4.jpg img5.jpg target.gif
@delay:  centi-seconds (1/100 seconds),  "500" means "5 seconds", "100" means "1 second" => (default value is 100.)
@loop:  "0" means infinite loop, other values 
@img[1-N].jpg: SOURCE JPG IMAGES, please arrnage it by sequence
@target.gif:  The target GIF