You get a certain amount free with signup - i forgot how much but their web site will tell you. they have free ways to add more - facebook, twitter, referals (500mb per referal signup) and couple others that i forget. I currently have 6.2bg of space - you can also purchase space as well.
You are not allowed to view links.
Register or
Login - give it a look - there is also microsoft skydrive as well, but I stuck with dropbox, as all my computers and cell phone are linked together.
Free acct starts at 2gb and can go up to 18gb, you can go up to 500gb via paid plans as well - they start at 9.99 a month.
Myk