Install tint2.

$ sudo apt-get install tint2

Edit the config file (~/.config/tint2/tint2rc) to customize.

If you want to enable autohide, add

# Panel Autohide
autohide = 1

to the rc file.

You should also add tint2 to the list of startup programs. See how to run programs during GNOME startup

You should read the full tint2 configuration docs.