Everything in @koanhead's answer is absolutely right. But what you seems to be asking for is an easy way to face file permissions issues, this is very simple.
If you are using terminal, you can:
man chmod and
in order to learn the appropiate usage of those commands. There are lots of stuff in the net, but you can be sure that the manuals in your system correspond to the command that you can use IN your system.
For a simple guide
You must have in consideration that you can change both file permissions and/or file owner by using both the commands I gave you above. The rules are simple:
chown will change the owner of a file/folder. A folder's owner can be changed even recursively (by adding the -R option). This way:
sudo chwon USERNAME ITEMNAME -R
After which USERNAME will have full domain on ITEMNAME's contents (ITEMNAME can be a file or folder).
In order to do several tasks, and depending on the result that you expect. You can:
sudo chmod 777 ITEMNAME -R in order to recursivelly allow everyone to perform any task over ITEMNAME, which can indeed be a file or folder. After that you can change the file/folder permissions in order to fit your needs.
What I mean is that, if you wish to perform any task on your file/folder without restrictions, make it editable/writable/deletable for anyone (with 777 permissions) and go ahead. After that, make sure you restore the appropiate permissions to it.
Additional information on how to set proper permissions was dropped in a wiki link on @koanhead's answer.