The List<T> has a constructor that accepts an IEnumerable<T>:

List<string> listOfNames = new List<string>(names.Split(','));

I prefer this because it prevents a single item list with an empty item if your source string is empty:

  IEnumerable<string> namesList = 
      !string.isNullOrEmpty(names) ? names.Split(',') : Enumerable.Empty<string>();

Use Split() function to slice them and ToList() to return them as a list.

var names = "Brian,Joe,Chris";
List<string> nameList = names.Split(',').ToList();

Split a string delimited by characters and return all non-empty elements.

var names = ",Brian,Joe,Chris,,,";
var charSeparator = ",";
var result = names.Split(charSeparator, StringSplitOptions.RemoveEmptyEntries);

If you already have a list and want to add values from a delimited string, you can use AddRange or InsertRange. For example:

existingList.AddRange(names.Split(','));

string given="Welcome To Programming";
List<string> listItem= given.Split(' ').ToList();//Split according to space in the string and added into the list

output:

Welcome

To 

Programming

Use the Stringify.Library nuget package

//Default delimiter is ,
var split = new StringConverter().ConvertTo<List<string>>(names);

//You can also have your custom delimiter for e.g. ;
var split = new StringConverter().ConvertTo<List<string>>(names, new ConverterOptions { Delimiter = ';' });