How do I create users with limited access to apps?

How do I create users with limited access to apps?

I want to create 2 (for now) external user types who have access to only specific apps, and who go straight to the home screen showing only those apps whenever they sign in to Zoho. I dont wan't them (under the signon I give them, anyway) having any access to any parts of Zoho not relevant to their work role. The key application they will be using is Docs, but they can also see mail (as a user) and maybe a couple of others. Their key work product is going to be in Zoho docs so I really only want them using that and communications about their work product and status.