hi, I just got my macbook air and I cannot seem to be able to search my folders in Finder. I am only able to get results on "This Mac"... any help would be appreciated.

"This Mac" includes all files and folders on your Mac, unless you've excluded any from indexing by adding them to the list in System Preferences > Spotlight > Privacy tab.

If running the search from a Finder window, you also have the option to limit the search to just the open folder, or to external shares if you have any connected.