notepad++ user defined regions with folding

Another simple way is just to add a comment marker followed by open-block to begin a block, and a comment marker followed by end-block to end a block. In C, C++, Java, Javascript, etc. it would look like this:

//{

//}

For version 6.5.5 and above:

Under the menu "Language" there is a menuitem called "Define your language..."

In the tab "Folder & Default" is a group called "Folding in code" where you can enter an "Open"- and a "Close"-Keyword.

For versions older than 6.5.5:

Under the menu "View" there is a menuitem called "User-Defined Dialog..."

In the tab "Folder & Default" you can enter a "Folder Open Keyword" and a "Folder Close Keyword"