Add role to the customer and give certain permissions in Magento

I am working on the website where by using magento I need to create an account when the user is registered, then I need to give that user permission to add products to my predefined categories. I don't know how this could be done. And I real开发者_如何学运维ly need help with this.

I think you're looking for a dropshipping extension. This one is said to be one of the best: http://www.magentocommerce.com/magento-connect/magento-vendor-dropshipping-extension.html There are few of these types of extensions, so a quick google search will show you all of them.

are you referring to a customer on the front-end or an admin user on the back-end?

For an admin user you can limit a admin users permissions by assigning them to a role that can only interact with the catalog module.