Memory and disk space are two completely different things. How much RAM is installed in your computer? How much free disk space do you have? They are two separate things. If you can provide that information then perhaps we can help you.
In addition to re-iterating the point made above by Jim Hess that disk space is not memory and you shouldn't confuse the two...
Let me add: Deleting photos almost never solves anything and causes problems as well.
And as far as a phone number goes, I don't know that there is a definitive number that would get you the help you are looking for. In most instances you will be referred back to the forum. There are a number of knowledgeable users who offer assistance here. If you can clearly define your problem someone might be able to provide the answer you are seeking.
This sort of error message only comes up for Lightroom when your hard disk is full. Indeed this has nothing to do with internal memory as that will be intelligently be dealt with. If you have a mac Book Air that is not so surprising as the cheapest versions come with very small hard disks and if you shoot raw with any recent camera, you'll fill up your hard disk very quickly and you can probably only store a few months of pictures if you are a typical photographer. So the bottom line is that you need to create some room on your hard disk. You should move some of your originals to an external hard disk. You can also delete some of your backup copies of your catalog file that Lightroom automatically generates every few days and that quickly gobble up hard disk space. So first figure out how full your hard disk is. To see that, go to the apple menu, hit -> About this Mac -> More info->Storage. You should see your internal hard disk on top and you'll find that it is almost entirely full with photos. Now find your Lightroom catalog file using Finder. It is usually in a folder in the Pictures folder in your home directory. You should see a Lightroom 5 Catalog.lrcat file, a previews file and a folder called backups. Inside the backups folder, you'll find a lot of subfolders. They have names that show the dates the backups were created. If you have backups of your entire hard disk, you can delete these backups when they are older than a few months. I usually only keep the last 4 around. Just drag the folders into the trash can on the dock on the bottom of your screen and empty the trash. This will probably free up enough space that Lightroom will already run again. Now start thinking about where you will want to store older images. If you have a good USB3 or Thunderbolt hard disk that is probably the best option. There is a video here by Adobe that has some instructions on how to do this: Is Your Hard Drive Full? Here’s How to Move Images to Another Drive in Lightroom. « Julieanne Kost's Blog If that doesn't work because you don't have enough hard drive space to run Lightroom yet, here is another set of instructions to move your files using the finder to the other hard disk: How do I move only my photos to another hard drive, leaving the catalog where it is? - The Lightroom Queen. If you follow that, as soon as you confirm all your images are on the new hard disk, you can delete them from your internal one. She is not so clear about that part but if you don't delete the originals that you moved off you don't free up space. You should move the folder structure over to the new hard disk and then reconnect the folders in Lightroom. That should make it refind all your images.
That said, if you are uncomfortable with the computer in itself, your best bet is to find a local photography club. There is invariably a Lightroom savvy person in there that could help you move your files. That might be your best bet if you are uncomfortable moving these yourself. A general mac savvy person like you would find at an Apple store or so generally will not be able to help you with this except when they are photographers themselves and know Lightroom. You might get lucky with that.