Have you ever tried to email a very large file and had it fail to go through? There are a lot of complicated reasons why this happens, but a general rule of thumb is to avoid email attachments larger than 10MB. When you have a file, or group of files, larger than that, you can get around this limitation by using other methods, most of which email links to files that are then downloaded from a server somewhere (generally called a "cloud"). Like many free services on the web, they exist to entice you to buy a sturdier version of the same product. Here are a few services you can (at least as of this writing) use for free:
free version: http://free.mailbigfile.com/
Very simple interface. 2GB limit. 5 files maximum at one time.
Free requires an account. 2GB limit. 250MB file size limit. More complex and more options.
Simple interface. 2GB limit. You must click on SKIP to get to the free version. It is a bit confusing trying to avoid the paid version, but this is true for all of these, to some extent.
Using Dropbox to send a file requires first opening a Dropbox account. You can sign up for a free account direct from my Partners page. There are a few ways to use Dropbox for file sharing, but here is one I like. Put the file you want to share in your Dropbox folder. Right-click (control-click) on it and choose Share Dropbox Link. Log in to www.dropbox.com. Click on LINKS. Select the file and click on the gear icon. Copy the link or choose from other link options.