If the spool is cone shaped, it is meant to unroll from the top of the cone. It is cross-wound (or spiral-wound). If your machine has a second spool that lays horizontally, then it is the one you want to use for cone-shaped thread. You can purchase a thread stand for your cone shaped thread if it will not fit on your machine. Joann carries them for about $20.
A typical all-purpose spool of thread unwinds from the side (parallel-wound). Use your vertical spool pin and make sure that it unwinds from the back.
Serger thread is typically cone shaped and is two ply, while all-purpose thread is three-ply. Two-ply thread is lighter weight and therefore doesn't bulk up as much in a serger stitch.
It is also important to use the felt pad that goes under your thread and also the cap that goes on top of the thread spool. If you're having trouble with your thread tangling, it can be related to any of theses things.
This is unrelated to the subject, but if you have misplaced your nets for your cone shaped thread, you can cut tubes out of your nylons and use those. This can be important when you are using a very unruly thread like monofilament.
Last edited by SewingSew; 08-04-2016 at 05:15 AM.