I can't connect my acer projector to my macbook pro! I read online that I need a VGA adapter but it didn't work. I also read some says I can use the same cable to connect the printer to the USB port and I tried that again but it didn't work as well. Please help as I REALLY need it for teaching.
Here are the ports I have. The ones I crossed out are the one for modem DSL and the USB port! as u see nothing seems to be for the projector.
and I found this on apple store and want to know if this is what I need because i think I got the wrong one.
Gigabit Ethernet (for network connections, or in your case your DSL modem or router, crossed out)
Firewire 800 (for external HDDs or other devices like a camcorder or audio hardware, faster than USB, not crossed out, but not helpful in your case)
Thunderbolt (for connecting external devices like HDDs or displays or any other kind of peripheral you can think of with a Thunderbolt port, not crossed out) - this is the one you want to use with a Mini DisplayPort to VGA adapter (more info below)
USB 2.0 (twice, for external HDDs and such stuff, slow, crossed out)
SD Card slot (crossed out)
Anyway, as mentioned before, Thunderbolt is the port you want to use.
Btw, the image of the adapter you selected does not really show the port for the Mac, it can be either a Mini DVI, MDP or Micro DVI port, but again, you need a Mini DisplayPort to VGA adapter.
Mini DisplayPort is the current digital standard on all current Macs to transfer video to an external display or TV. It has been introduced in 10/2008 with the release of the Unibody MacBook and MacBook Pros and has gradually been adopted on all other Macs.
MDP is capable of transmitting video, and since 2010, audio too. MDP is a miniaturised version of DisplayPort. It is also license free and can support resolutions of up to 2560 x 1600, which Mini DVI and Micro DVI are not able to do.
Since 2011, all Macs come with a Thunderbolt port, which is meant for fast data transfer and also as means to connect to an external display device to mirror or extend the Mac's screen.
To learn more about Thunderbolt (TB) and its compatibility with Mini DisplayPort (MDP): Introducing Thunderbolt
MDP adapters and cables can be bought online from:
Please help as I REALLY need it for teaching. 
