How To Add <br> In String After Counting Particular Characters

I want to display description of product in gridview, but i want to display only 15 characters on one line, I want to break it after 15 characters, I have written countchar function as follows:

public int CountChars(string value)
{
bool lastWasSpace = false;
foreach (char c in value)
{
result++;
lastWasSpace = false;
}
return result;
}

and called function as:

string description="sdfsdfsd sdfsdf sdfsdf asdfsa dfsda safsaf sdfdf sdfs sdfsdf sdff sdf ";

CountChars(description);

And i want to check:

if(result>15)
{
after every 15 characters i want to break the line.
}