how do i reach my contact list when sending emails? I have some contacts that appear in the left box, but not all of them.

When I want to forward a email and I open the reply then click on forward, I get a partial contact list on the left. some of my contacts are there, fine but how do I get to the rest of my contact list? it appears that the left box is from frequently mailed contacts.  Maybe eight on in that list, but the ninth one is in my contact list. how do I get to that contact list to add with the other eight I selected from the left pop up box?