Hi,
Handle the KeyPress event for this textBox and put a single condition like.
if (textBox1.Text.Length==0 && e.KeyChar==' ')
{
e.Handled = true;
}
else
{
e.Handled = false;
}
Here textBox1 is your textbox. This code will prevent user to enter space at begining of TextBox.
Now, If you want to validate the data
Then You need to check first character of TextBox whether it's a space or not.
You can find first character like this
char FChar=textBox1.Text.Substring(0,1);
Regards
AR