BSD would like to help you!
Here is some info you will need and need to understand.
In ordering a new string set you will need to have the following info on hand.
1. Make of bow. examples: Hoyt, Matthews, Pse, Elite etc.
2. Model of bow. Examples: (Pse) Brute, (Matthews) Chill x etc.
3. Year if possible. But not always necessary
4. You will need to know what string set style you have.
Single cam (1 Bow String,1 buss cable)
Dual cam (1 Bow String 2 buss cables)
Binary cam (1 Bow String 2 control cables)
Hybrid cam (1 Bow String 1 buss 1 control)
Also there are 4,5 and 7 piece sets in the more modern bows
four piece set (1 Bow String, 1 buss, 1 yoke, 1 control)
five piece set (1 Bow String, 2 yokes, 2 controls)
seven piece set(1 Bow String, 4 yokes, 2 controls)
5. You will need to know, String length, Yoke length, Cable length, Buss length these are usually found on a limb sticker on the bottom limb close to the riser.
In some cases your draw length will help in finding the lengths.