C# : Parse a Text File

There are no real short cuts when it comes to stuff like this.
Firstly, it seems to be organised in lines: so start by converting it to a collection of lines.

string[] lines = File.ReadAllLines(path);

Then, I would probably set up a List<string>for each type you want to extract:

List<string> Points = new List<string>();
List<string> PointDim = new List<string>();
List<string> Size = new List<string>();
...</string></string></string></string></string></string>

Then I'd start looping through the lines separating out the lines into the appropriate collections.
Finally, Id start looking at the collections, and converting them into internal classes (or collections of internal class instances)

IEnumerable<string> allLines; 
string filePath = @"C:\data\data.txt";
 if (File.Exists(filePath))
 {
  //Read all content of the files and store it to the list split with new line 
   allLines = File.ReadLines(filePath);
 }

 //all Point 1 lines
 IEnumerable<string> point1Lines = allLines.Where(d => d.StartsWith("Point1", StringComparison.CurrentCultureIgnoreCase));

foreach(string line in point1Lines)
{
  string[] values= line.Split(' ');//either space or tab or others as your file contain seperator  
  for(int i=1; i <words;>  {
      string value = values[i];// skip index 0,it contains label, remaining are point data
     //logic goes here
  }
}</string></string>