List<int> myList = GetListOfIntsFromSomewhere();
// This will filter out the list of ints that are > than 7, Where returns an
// IEnumerable<T> so a call to ToList is required to convert back to a List<T>.
List<int> filteredList = myList.Where( x => x > 7).ToList();
using System;
using System.Collections.Generic;
var vals = new List<int> {-1, -3, 0, 1, 3, 2, 9, -4};
List<int> filtered = vals.FindAll(e => e > 0);
Console.WriteLine(string.Join(',', filtered));