For that, I learned on the job--
I had a skillset of:
A. Promoting products at events as a Brand Ambassador
B. html, css, and basic frontend javascript self-taught skills (from ebooks, youtube, udemy).
With skills A & B, I successfully justified that I should be hired into an entry level digital marketing role, where I used Marketo to email-spam B2B and set up web landing pages.
Once I had that initial job using Marketo software at a B2B software company, it was much easier to lang other digital marketing roles.