I'm familiar with the equations but now these q's.
Thee questions are just about practical application of the equations you know.
Say you are asked to prepare 200 mL of 0.5M NaCl solution.
First, calculate mass of NaCl that will be present in the solution - that can be done with the equations you alredy know.
Weight correct amount of NaCl.
Dissolve in some smaller amount of water than target volume.
Fill up to 200 mL.
You can't use 200 mL of water, as the final volume will be higher and the final concentration will be in effect lower.