The SVT-40 can be sort of tricky, and it wasn't really intended to be separated from the stock on a regular basis (it would have been sent back to a depot armourer if it required it), but field-stripping is pretty simple. Ensure the rifle is empty and the magazine is removed, with the rifle cocked. At the rear of the receiver, there's a notched flap that rotates to the side, exposing a collar/plunger inside a hole. Pressing in on that collar releases the trigger guard/floorplate from the bottom of the rifle, which swings down and out. The top cover on the rifle also holds in the recoil spring and guide, with a semi-circular notch that the rear of the guide-rod fits into on the bottom rear of the cover (if it slips out while you're taking it out or putting it in, it can launch the rod at your eyes, so be careful). When you've got the recoil assembly separated from the cover, the cover will slide forward and lift off, folowed by the bolt in the same way. That is about as far as most people are going to go without some specialized tools for removing the stock bolt and the gas piston, but it does let you clean most of the rifle. Since most 7.62x54R is going to be at least mildy corrosive, it's a good idea to slosh out the gas system with Windex (the ammonia gets rid of the worst of it), and then blow it out with compressed air, folowed by a light oiling.
Gun control in Canada: making the streets safer for rapists, muggers, and other violent criminals since 1936.