Here you go: DISASSEMBLY & ASSEMBLY OF 1895 WITH PICS
Step by step with pictures and instructions. Your 336 will be the same except you do not have the bluge in the mag tube so no twisiting required and you likely have barrel bands but that's pretty straight forward.
If you don't already have them, do yourself and your gun a favor and invest in gunsmithing screwdrivers. I like Grace Gun Tools and if you contact them they will sell you a 5pc Marlin set for $38. But there's lots of options.
Also, click the links in my signature to discover a wealth of outstanding information on all things Marlin.