Once the Memoir has been selected you will see the action bar as show below.

The buttons from left to right are
- Chat
- Use/Do
- Search/Examine
- Inventory
- Show Memoir
Additionally you can click the Red X to close the Memoir. This will bring back the Picture frame. If you want to choose a different memoir you can click the Gray Up arrow on the left side it will reopen the Memoir Selection Menu.
Chat
To initiate a chat you would select the NPC or even item if the Author has build their adventure that way. If that selection is in the current Memoir a Dialog window will pop up as shown below.

In the one window you will see what the NPC is saying to you and the other will allow you to pick your response to them.
Use/Do
This is a feature being worked on and is not currently available
Use/Do allows you to interact with items or even just in location in the game. These would be described in the quest log as objectives.
Search/Examine
This is a feature being worked on and is not currently available
As with the Use/Do this is done at a location or on an item, even an NPC. Depending on the Memoirs objectives.
Show Memoir
This will bring up the Memoir. In this you will see the original description and any Quests that you have picked up. You can get multiple quests in any Memoir.

From here you can select a quest to see your progress in it.

Each quest could have multiple objectives. These will grow as the quest continues and you learn more about it. On the right side is a journal of things you have done or seen in the quest. If you select an objective on the left the Journal entries for it will highlighting on the right.
You close the Memoir by clicking the Red X on the right hand side of the book.
Game actions
This is a feature being worked on and is not currently available
The memoirs integrate into Normal LOTRO play actions listed below can be used to further quests.
Killing Mobs
This works pretty much the same way Lotro quests do. You need to kill x number of a mob and as you do this quest will further.
Fishing
Sometimes a quest will require you catch specific fish.
Birding
Sometimes a quest will want you to see a specific bird out in the wild.
Emoting
Quests may require emoting either alone or even to specific items. Say Petting a horse.
Moving Windows
You can move windows by holding down ALT and dragging them. The positions you choose are account wide.