K-x lenses

I am very new to photography, so please bear with me. I have a K-x with the kits lens, but I also have 2 old lenses (SMC Pentax-M 1:2 50mm and QTII auto zoom 1:40-5.6 f=70-210mm) that my son had with a K1000. Do I need an adapter or can I use settings in K-x to use these lenses? Like I said, I'm new, so please be patient with the simple questions.

Any Pentax lens will fit any Pentax body, that's the beauty of the Pentax system. Functionality may vary, check you user manual, which lists the possibilities.

Generally, for manual lenses you will have to set Using Aperture Ring to Permitted in the Custom menu.

Btw, the only way to learn is to ask, and to practice...

As long as they are K-mount(bayonet fitting)of course.

Earlier Pentax (and others) with the M42 (screw mount) will also fit with use of the correct adapter which are available from Pentax or 3rd party manufacturers.

The zoom probably won't be that impressive, but the 50mm should be pretty sharp. You'll need to do the following:

In the camera menus, set "use aperture ring" to "allow"

Switch to manual focus and either Av or M mode

When you switch on with the manual lens fitted the camera will ask you to dial in the focal length for shake reduction - just use the thumbwheel to select and press ok.

In Av mode your camera will meter and shoot with the lens held to its largest aperture (f2 in this case). In M mode the aperture ring will make a difference, but you need to use stop-down metering. You set the aperture, press the +/- button, and the camera will stop the lens down (to your selected aperture), take a meter reading, and offer you a shutter speed.

Focussing manually can be tricky - you will still get the focus confirmation light (a green hexagon in the viewfinder) and the beep though, which should help.

Please don't get me wrong here, but I would like to point out a couple of inaccuracies in your description:

The Custom menu 21 says to set "Use Aperture ring" to "Permitted" (not "allow"), page 284 in the manual.

The +/- button allows you to set the aperture using the eDial. To take an exposure reading you should press the Green button, which should be programmed to control Tv shift in Manual mode (page 102).

This may seem pedantic, but I feel that accuracy is important, especially for users with little or no experience