If you'd like to invite a colleague to participate on Science Exchange, there are two options:
1) You can add them as a collaborator to specific orders, in which case they will only receive notifications and access to those specific orders. Please see this article for a guide on how to set your order Collaborators.
2) You can add your colleague to your general storefront account. If you give them Admin access they'll have access to all orders. Lab Admins also have access to the Settings tab and can edit information on your Storefront, in addition to being able to respond to customer requests. The other option is to add a Lab Member without giving them Admin access to your general account. Please see this article for a short description on the privileges an Admin and Lab member have.