However, when you want to present a certain thing to other people and you have a numerous audience you need a bigger display if you want everybody to see whatever you want to show: photos, movies, a presentation in Photoshop or PowerPoint. You can use a large external monitor, of course, but this applies only to a few people. If you want to make a presentation in front of a class or in front of the entire staff in a company for example, using the conference room, you will have to do better than that. The best solution for this is a video projector. So you will have to connect the Macbook Pro to a video projector and use it to project the images on your computer screen onto a white wall or white screen.The surface on which you will display the images will be a lot bigger, so will the success of the presentation.
However, these video projectors are not made for a normal connection with a laptop, but normally it is used with video or DVD players or TV or slides. So you will have to find the right adapters to use when you connect the Macbook Pro to a video projector. I am pretty sure that the video projector already has a VGA cable that is used to connect it with different devices, so what you really need now is an adaptor VGA to the mini-DVI port of your Macbook Pro.
Once you connect the two devices, make sure your Macbook "reads" the video projector, that is if it appears on your laptop as an external monitor or something like that - the place where the out signal will be sent in order to be displayed. Sometimes, depending on model of the video projector, you will also need to install the video projector's drivers on your Macbook Pro or else they will not be able to fully co-operate. The cables and adapters that you need are normally very cheal , around $20, and you can buy them from any store that sells computer items and accessories, either online or directly in the store, so make sure you know everything you need before starting to prepare for the presentation. It would also be nice to come and have a general rehearsal one day before the event in order to fix the eventual problems.
If you are not too much into the technical department, just read the Macbook user's manual and you will see there is a special chapter for this kind of problem, illustrated with pictures and giving you detailed instructions of what you have to do. Or you might read some other related articles or even find a video tutorial that you can easily find on YouTube. Good luck and let me know if you succeeded.