How did Jesus learn obedience in order to become the source of eternal salvation?

Hebrews 5:8-9:

Though he were a Son, yet learned he obedience by the things which he suffered;

And being made perfect, he became the author of eternal salvation [soteria]

unto all them that obey him;

soteria:

 #4991 σωτηρία soteria {so-tay-ree'-ah}

 feminine of a derivative of G4990 as (properly, abstract) noun;
    TDNT - 7:965,1132; n f

—Greek Word Study (Transliteration-Pronunciation Etymology & Grammar)

 1) deliverance, preservation, safety, salvation
    1a) deliverance from the molestation of enemies
    1b) in an ethical sense, that which concludes to the souls safety
        or salvation
        1b1) of Messianic salvation
 2) salvation as the present possession of all true Christians
 3) future salvation, the sum of benefits and blessings which the
    Christians, redeemed from all earthly ills, will enjoy after the
    visible return of Christ from heaven in the consummated and
    eternal kingdom of God.

 ++++
 Fourfold salvation: saved from the penalty, power, presence and most
 importantly the pleasure of sin.  A.W. Pink

—Thayer’s (New Testament Greek-English Lexicon)

Feminine of a derivative of G4990 as (properly abstract) noun; rescue or safety (physically or morally):—deliver, health, salvation, save, saving.

—Strong’s (Greek Dictionary of the New Testament)

  • #4991.
  • σωτηρι´α
  • sōtēria; from 4990; deliverance, salvation:—
  • NASB – deliverance(2), preservation(1), salvation(42).