post up

Short definition from Wiktionary

Verb

1. 1
   To affix a notice, announcement etc, to a post, board, wall or the like.
2. 2
   To enter any information, data etc (into a register, account, record etc).
3. 3
   To establish a position in the frontcourt on one side or the other of the free-throw lane, especially used against smaller defenders.
4. 4
   To occupy a position.

Noun

1. 1
   The process of posting up.