The following thing you may need to know:
.How to script
.how to Build (With Cframes).
.Decal making
.retexturing
.animating (using the animation plug-in).
.creating SFX and music
(Note: this is not a serious project, it's for fun). (You can know 1 out of 5 of these listed).
first off you did not mention of what you have in the so called "RPG" secondly , you did not mention anything about the "RPG" like what the concept is , what's it based on... Thirdly Nobody is going to join , If you don't describe the "RPG"
@sly37 The person who participates will already know what an RPG game is with their prior knowledge. They will think of Legend of zelda. (For example)...
Also, I will discuss all of the game's stuff with the person personally.