Commonly, all guitars that you see in the store have proper set up.
This means that their strings are correctly strung already.
Correctly strung guitar strings will not produce any buzzing sounds, when played at whichever frets.
At the guitar bridge, the six pegs will have to be inserted properly.
These pegs look like screw and they interlope with the guitar strings.
Think of it like a needle and a single thread.
The pegs need to be sturdy and made to fit the holes.
If you have six strings, you will have six pegs.
Number of strings equals the number of pegs.
Choosing guitar strings depend on the guitar types you have; electric, acoustic, jazz, classical or bass.
The nylon strings are a standardized usage for the classical guitars.
It is never good advice to use more heavy strings on the classical.
A classical is not meant to suit high tension.
As for the nylon strings, the lowest of the 3 strings are made from copper wire (wound) with strands of nylon.
Meanwhile the upper three strings are 100% nylon material.
You would want to choose steel strings for acoustic guitars.
Whether it is folk or conventional, they have the same meaning as acoustic.
Likewise, the bass strings are made from nylon or silk on the outside.
As for electric guitars, metal strings are best chosen.
Metal strings are capable of producing sharp tones and heavy sounds that are essential in rock music.
As a conclusion, experiment with different brands of strings.
The core and winding materials will differ between manufacturers.
You must know that guitar strings are available in light, medium or heavy gauge types.
The lightest gauge has the best flexibility and elasticity, making playability an easier thing to do.
Experimenting with different types of strings is the key to producing better sounds that you like.
It is all up to individual taste.