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Notice, that the "~" sign disappeared, as you went out of your personal home directory from /home/username to /home. The directory "/" is the so called root directory - you can't go downwards from here as all directories are based here.
To change directly to a specific directory, you may use:
drwxr-xr-x 3 username usergroupname 4096 2009-01-26 07:20 simgear
First, every item has its mode bit, shown on the very left in a scheme of ''drwxrwxrwx'', followed by a number, the username of the owner (should be the same as of the current user!), the name of the group of the owner, file size, its last change date and its name. If there is a "-", the specific mode bit isn't set.
The first ''d'' in some of the items indicates a directory. Then, three groups of ''rwx'' follow. Each ''r'' means "file/directory may be read", each ''w'' means "file/directory may be written", each ''x'' means "file may be executed".