chown -R us ~your/Base
For the non-Unix-savvy, let me break that down:
chown: change ownership of a file
-R: change ownership recursively, go down the directory tree and change all files
us: the user ID which will become owner of the files
~: home directory of a user
your: a user ID; ~your is the home directory of the user "your"
/Base: the directory named Base, containing files the user associates with Bases
Therefore
chown -R us ~your/Base
means
All your Base are belong to us.