If the lens isn't an A lens you need to set the camera to allow use of the aperature ring. It's in the manual. I'm at work. Manual is somewhere at home. Otherwise I'd look it up for you. But if you do a search on this site there's been a thread or 10 about this.
George
P.S. See you spent your first post asking a question. Take a trip on up to "Introductions" and get a right proper welcome.
P.S.S.
Actually your answer may be in the sticky right at the top of this part of the forum.
https://www.pentaxforums.com/forums/pentax-beginners-corner-q/59272-shooting-...x-dslrs-f.html