Can you have more than one 4 port slinglink turbo on one net work.
Yes. You can have up to 16 Slinglinks (1-port or 4-port) in use. The product page talks about that, here's the relevant bit:
If so, what do you do to connect them.
Generally, you simply plug them in. There's a utility you can use to adjust the configuration if needed. It's on the product page I linked to above.
Hope this helps,
Just to expound a little on the above.
It's a little-known fact that the SlinkLink Turbo conforms to the Powerline Ethernet Adapter standard. So, it will work with other Powerline adapters you might already have. For example, you already have a Netgear Powerline Ethernet adapter, just plug it into another outlet in the house and you will be connected to the Internet. SlingLink Turbo will recognize it in the network and adopt it into the configuration. You can connect up to 16 Powerline adapters in your house and all of them will talk to the SlingLink Turbo connected to your router.