removing cap

[NYGiants]

i have an older sunfish type boat and i noticed the cap is coming off at the bow. i have 2 quesions a) how can i remove the cap and b) how can i reseal it

http://s499.photobucket.com/albums/rr359/JasonKiddFan273/?action=view&current=sunny2.jpg
heres a general picture of the boat.