Yes - GHC students can use any library at any University System of Georgia college or university. Just take your GHC student ID with you to KSU.
To use the computers you must go to the KSU card services and get a (FREE!) KSU card. That will give you access to the computers on the Marietta campus.
KSU Card services are in the Mack Wilson Student Center upstairs in room 250A. Their hours are:
Monday: 7:30AM–6:30PM
Tuesday: 7:30AM–6:30PM
Wednesday: 7:30AM–5:00PM
Thursday: 7:30AM–5:00PM
Friday: 7:30AM–2:00PM
Saturday & Sunday: CLOSED
