Characters must be on the guild site's Character List or Guild Roster to be added to events in rapid. 

If the character
does not exist yet the Raid Leader or guild master can add the character to their own profile in an 'Unclaimed' status using their Add
Character link on their Character Tab of their user profile.  When the person who owns that character later joins the guild site
they can then "Claim" the character from the Guild Roster. 

Items

Items can be added to any event in the raid

Items can only be awarded to attendees of the event the item is associated with

In its simplest form the process for adding DKP is this:

Add a Raid using the "Add Raid" link on the left

On the next page click the "Add Event" button. 

Use the form to set the DKP amount, then submit the page. 

If you find you don't have any events available or the event that you want isn't available add them on the Manage Event Types page or using the form on the right

The Raid Import functionality will create events named after the bosses as necessary, you don't need to create them by hand. 

Use the form to add the Attendees for the event

If you find that a character isn't available make sure they are set to eligible on the Admin->Members->Character List page and that they are on your Raid Roster so that they are active

On the next page (the Raid Details page) add items as necessary. 

If the character you want to assign an item to isn't availble then edit the vent and add the character as an attendee.