How do I get a specific set of sprites from a sprite sheet?

Hi, I'm a strawberry flavored Oreo. I hope this is the right place to post this.

So, I'm working on a fanmade Pokemon game in RPGXP/Pokemon Essentials. I was looking up overworld sprites for the trainer class "Hex Maniac" because they're not in Essentials and I need them for a specific part of my game. 

After a while of searching, I found Spriters Resource, which has a sprite sheet of all the overworld sprites for every NPC in RSE. I was happy to find this, because it's the only place I've seen with the Hex Maniac overworld sprites. 

This is where I need help, because I have no experience with computer art or photo editing. In order to use them in Essentials, I'd need a sprite sheet of their overworld sprites on a transparent background. How do I take just the Hex Maniac sprites specifically from this photo, and make the background transparent? (Credit for the sprites will be given as requested by the photo)