To add another collection click on the circle with the three lines left of the collection name. A menu will appear on the left side. The first entry is “Add New Collection”. If you click on it, you can enter the name of the new collection. After doing that and pressing OK it will get created and directly activated.
To change the active collection, click on the circle with the three lines left of the collection name. A menu will appear on the left side, with all the collections you currently have access to. That could be ones you did create yourself or ones that other people gave you access to.
People can get added to a collection by clicking on the three yellow dots right of the collection name. There you can then select “Share Collection”. On the appearing site, you can add users by supplying their email addresses. They will then get informed via email that they got access. For each person, you can then also set what rights they have.
Admin -> Can add and remove users. Could also remove you from the collection
Tag -> Create/remove tags
Entries -> Add/remove entries and apply tags
The permanent collection is for everything you want to save long-term and that you can share with others. You can create as many of them as you want.
A temporary collection is a place where you can simply dump some pages. That gives you the possibility to inspect them further. The ones you then want to keep can then get promoted to the permanent collection and all other ones can simply get trashed. Each user has only one of it and it can not be shared. The collection which is currently active while being in the temporary one decides where entry get promoted to.