Take a look at the lens at this url: http://cgi.ebay.com/YASHICA-AUTO-YAS...QQcmdZViewItem
The top set of numbers is distance in feet and meters. The lower is the actual f/stop. Note that since f/1.7 isn't so much wider than f/2, the lens maker shows the widest opening; f/1.7, and a dot for f/2. The middle scale has a dot with matching numbers to either side. The dot is for f/2, again since f/1.7 and f/2 aren't so much different. Those numbers to either side show you where on the distance scale, things are presumed to be in acceptable focus. Hopefully your lenses have the same type of markings.
Note that it isn't entirely accurate, but is for most subjects. In actuality, the depth of field will usually be about 1/3 in front, and 2/3 behind the actual place you are focused on, called the plane of focus. The plane of focus is an imaginary line parallel to the film plane, right at the distance you are focused at. The film plane is where the flat portion of the film is at, in the back of the camera, that receives the light for the photo.
Hope that isn't too confusing. BTW, if your lenses don't have those or similar markings, look at the instructions that came with your lenses. It is probably there regardless. That should get you started, but you might want to go to your local library or used book store for some books that will tell you the same. Or, you could google "depth of field."
Good luck, and don't hesitate to ask questions. I am sure some others will chime in with better explanations, maybe even photos of the same lenses you have. Some may have even done so while I was typing this.
Edit: When you look in books, or google, be sure to look for hyperfocal distance. It will give you some breathing room. You will note the lens at the above url is focused at infinity so some of the numbers are to the right of the infinity mark. If you set the aperture at f/16, you could then move the infinity mark on the distance scale (on the lens shown) and everything between the two numbers 16 would be in acceptable focus.