Here are the following roles you can choose from as well as a description of what you need for it. 

Emeralds - Graphic Designers

The emeralds are graphic designers. The colour that represents them is green. They will be making any graphics that is requested, from covers to characters aesthetics and much more. They will be using their talent but you can't steal their work and you have to complete the payment they require. 

Rubies - Editors 

The rubies are the editors. People give you chapters or stories to edit. Now, you don't edit it directly. They will send it to you and you will edit it and send it back, if they are pleased they will put up the edited version and give you credit. If they don't, you can come to me. Being an editor, they have to keep in mind that it is not your story, so they can't take over it. Yes, they can point out plot-holes, poor characterisation and grammar errors, but they can't make up the plot for them.  

Sapphires - Reviewers 

The sapphires are the reviewers. The colour that represents them is blue. Reviewers read stories and give the author some feedback. This is really flexible in terms of criteria - they can review whatever you feel like reviewing, though, I recommend that they also take what the author wants you to review into consideration 

Pearls - Face-Claimers

The pearls handle the face claim/cast shop. The colour that represents them is white. They handle casting requests. For example if someone requests, "I need a young boy that has brown soft hair and green eyes." The pearls look and finds their best matches for the client. Pearls will also give you names and their meanings, if you ask. 

Amethysts - Trailer-Makers [in desperate need!!]

The amethysts are trailer makers. The colour that represents them is purple. These make trailers for book using images and video clips. You need to be good with video editing for these. With your permission some may even be on YouTube.

Jewellers - Recommenders 

The jewellers read books (preferably completed books) and decide whether they should recommend it to others. Unlike reviewers, they don't give a detailed breakdown on what was good or bad. They simply recommend it if it's good, and if they think it needs work, they will politely tell you why and encourage you to consider an editor/reviewer. 

Quartz - Account Raters

The Quartzes are the account raters. They will visit profiles and give feedback as requested about different aspects of your Wattpad profile. Similar to the sapphires, this is the one for you if you want to review but you don't have the time to pour through books. Being a Quartz is especially useful for Wattpadders who don't write. Do keep in mind that as a Quartz, the profile they review is not their own, and therefore cannot take over it.