read up

Short definition from Wiktionary

Verb

1. 1
   To learn (about something) by reading.
2. 2
   To learn (about something) by reading: [with on or about]
3. 3
   To read previous or higher-up messages in a chat; to backread.

Adjective

1. 1
   Of an individual, well-versed or informed in a particular subject.