Minecraft on Macbook 10.5.8

When I put Minecraft on my toolbar at the bottom of my Mac screen, it is invisible, I installed everything on the launcher, then I click play.. and it says...
Client> Invalid memory access of location 0x0 rip=0x0
Client>
Game ended with bad state (exit code 139)

.. then crashes. HELP!
Sorry if there was already a post on this, I did scan through thugh.