Dropbox can help you in many ways. When you install this app on your computer, you will create a "dropbox" folder on your local drive. Any subfolders and files that you put into this "dropbox" folder are then kept in sync "in the cloud" (i.e. online).
So firstly, you now have important files backed up without even thinking about it!
Second, because they are "in the cloud" you can have access to these files wherever you are and if you have multiple computers (e.g. work and home, laptop, mobile) you can get to your files.
Third, it is a great way to collaborate on a project. You can grant others rights to your folders and you can work together on these files. The specific subfolder(s) that you share will be kept in sync with the team.
Dropbox gives you 2GB for free (which is a really decent amount of storage to start). If you need more space, there are low cost per month plans to step up.
(use the affiliate link above to sign up and I will get credit for the referral, thanks!)