I can't afford a new door so how can I repair it.
How much will it cost me to install a new door
In that condition, unless you get a steel cover plate to repair it, it's time to replace the door. Look for this item:
https://s3-media1.fl.yelpcdn.com/bphoto/RrkHH45lZUiGHlXLzZgy7w/o.jpg
Put little wooden screw or small nails/studs into the wooden door and apply the m-seal on it with mixture of wood powder, and colour it with same paint.
Note: Make sure m-seal and wooden mixture not go inside the latch/lock mechanism