Well, it's a tricky process both to work through, and explain. I'll try my best though. :)
There's two programs I use heavily for SP mapping:
1. HellishER's SinglePlayer Creator. It steps you through the entire process - in fact, it's possible to make a SP map with this tool alone. However, you can get much better results by using extra tools.
2. GenPathMaps. I use it primarily to convert the .raw pathfinding files into .bmps, which makes them much easier to edit.
Try Googling SinglePlayer Creator and try using that at first to get basic SP into the map. If you want me to help you out with writing strategies and trickier things I'd be glad to.
any tutorelouis or guides n how todo this your self