Be careful with that K-100 mech. It has some known safety issues, including using a bottom fire button. Bottom fire buttons have been known to "autofire" in pockets and purses. Even those with locking fire buttons, they can malfunction. Some models also have no vent holes, or vent holes which become obstructed when the mod is assembled; should a battery vent inside, the mod becomes a potential pipe bomb. Seriously, invest in a better designed mechanical mod.
Initially, build only normal resistance coils (1 ohm or higher) when first getting into rebuilding coils. There's a lot to learn before getting into sub-ohm territory. Once you have a couple of normal builds under your belt, then experiment with some sub0hm.
Be sure to have an ohm reader or digital multimeter to measure your coil's resistance. Never fire a coil which has not been already measured; and re-measure it periodically to insure it has the same resistance. A loose post screw can unknowingly alter a coil's resistance.
Start by selectively reading my Blogs. Information Resources for Your RBA, Battery Basics for Mods, Explain it to the Noob: Ohms Law calculators, Inexpensive Mech Mod and RDA, in particular.
Research and do more research. Know what batteries to use; know their amp limits. Learn enough about Ohm's Law so that you understand how the coil resistance will draw so much amps from the battery, and to never exceed that battery's amp limit.