Out of plumb?

I have a front entry door that doesnt seal well. The top left corner is not contacting the weatherstrip and I can see light through it. Is there an easy way to fix this?

 

When viewing the door from the outside, if the top left corner of the door is not contacting the weatherstrip, that means the top left corner of the door jamb (and the bottom right corner) needs to come toward the door. You might have to remove some trim to make this adjustment. You can try holding a block of wood against the door, then give it a firm whack with a hammer. If the door has been glued or nailed in place, it probably won't budge. It's always easier to push the door toward the exterior when you need to make such an adjustment. Pushing the door in toward the interior is usually not desirable.

Stores that sell doors also have wedge shaped foam pads that can be installed behind the weatherstripping at all 4 corners of the door, which often helps to eliminate that light that you can see at the corners of the door.