do you want a simple fade in or a fly in through the front?
If its a fade in, take the top (right if your on the right side, or left on the left side) then drag it until you got the fade you want, if you want a different fade type ( fade soft then hard or vice versa) you right click then choose which one you would like to fade as.
if you want a fly in(fly by) there is a transition for that just look for it in the transitions tab.