Spacemacs by default has the SPC key as leader.
Double check this in the .spacemacs file (which is by default in home directory).
Check that the following line exists in the configuration.
If this does not work check for boot up errors.
Check *Messages* buffer to see if there are any errors while booting up.
One other thing I notice is that the powerline has a blue color in it. This blue color means you are in emacs mode. When you were setting it up for the first time you might have selected emacs keybinding. In this case just delete the .spacemacs file then reopen.
When it first opens it will ask you.
What is your perfered editing style?
Select the below option
Among the stars aboard the Evil flagship (vim)