BRO signature


i read the document which is provided in website regarding signature framework.

But the thing which i cant understand is that where i have to place this file i.e i write a simple program with name hello.bro but i don’t know in which folder this file to place because in command prompt it always says cannot create a file.

Please tell me what can i do and also some information about how to write a signature code .

thank you

wishing your early reply