Read Ken's book: Designer's Guide to Spice and Spectre.

The basic ideas for finding dc op point, as well as for setting up the matrix for KCL and KVL (modified nodal analysis), are pretty much the same in good old Berkeley Spice as in Spectre.  Ken will tell you that Spectre is smarter about some things (ie, it actually checks that KCL is satisfied, whereas Spice just checks whether the change in currents is "small"), but these details are well beyond the level of questions you're asking.