First of all, you could look at google maps, but anyway...
Here's a map, it doesn't really show the bodies of water tho.
The bubble in the middle of the ocean is the Caribbean sea
The bubble pointing to the lake is Lake Nicaragua
Also, if you need to memorize this map, search up "The Central America Geography Song & Video" on you.tube, there's a song on there that's really helpful for memorizing the map. It should be the first video to pop up.
I hope this helped