Uh, well, it's all done in the UNIX file permissions. But if you're wanting to do anything other than anonymous file access, I recommend SCP, which is not as widely used, but it is more secure. If you want to use SCP, just use the SSH (which is something like "allow remote logins". But if you learn a little about file permissions, both will work the same way from there. Basically, on directories, if you set the eXecute bit to none, nobody can cd into that directory (which is pointess). You also can manually set it to owner, group, or world. In the numbered method of chmoding, that's OGW. Also, you can set Read to whatever you want, and Write to whatever you want. These can be used with chmod a+r for world readable, and so on. The numbering is a little different. Check out www.linuxdoc.org
for more information, even though some stuff won't apply.