Changing needles

Okay, I feel as though I have been knitting long enough that I should know this, but I guess not!
I am about to start the Cable scarf pattern from [U]Cables Untangled[/U] and I have to start off with size 7 needles and then follow a ribbing pattern for 4 rows and then switch to size 9 needles. How do I switch the needles? My assumption is that I just pick up a size 9 and knit the work from the size 7 onto the 9, but I’m not sure…Any help is appreciated!

Yep, that’s by far the easiest - just start knitting with the other needle.