What is the frequency when radio station branding is 106.3 energy fm naga?
CREATE TABLE "table1_23915973_1" (
  "branding" text,
  "callsign" text,
  "frequency" text,
  "power_k_w" text,
  "coverage" text
);
SELECT "frequency" FROM "table1_23915973_1" WHERE "branding"='106.3 Energy FM Naga';