Create UPK, save UPK. Create Map (.udk), save Map. Next time you load up something, load the UPK first, THEN load the Map. UDK is very much hierarchy based, so it will always look and load for came first or requires to be loaded first.
Ok, I'm confused. I'm relatively new to UDK and have yet (I think) to get my packages/map combos right. Take for instance the env I'm working on now; I created a package and saved it as Contents/Lab_Packages/Lab_Assets. I then saved the map as Maps/Lab/Lab. Low and behold, I now have a package within my Lab Map directory…
You have to save the content packages in the content folder. Otherwise UDK won't find them next time you start it and says that you're referencing to external content (external as in out of the content folder). You can open external packages by clicking the "open external package" in the content browser. It's in the lower…