You can get manuals at the Smith and Wesson website.
Ask a gunsmith for help
Recommend you find a good gunsmith.
check out this video: In general, Sigma pistols disassemble like a Glock. http://www.youtube.com/watch?v=O7ws0gAQlpY
Best left to a trained gunsmith. For normal cleaning, no disassembly is needed.
Go to S&W's web site and request a owner's manual. They will send it to you for free.
If you go to You-Tube and type in disassemble of Smith and Wesson model 915;there should be a video of the steps needed to take down your smith and Wesson semi-auto 9mm.
You can request or download a manual from the S&W website. If that doesn't work for you, find a good gunsmith.
Ask a gunsmith.
Smith and Wesson is the make.
If you contact Smith and Wesson directly,they should be able to provide the information that you seek.
Smith and Wesson 6909 Stainless steel semi-auto pistol stopped produvtion in 2001