error:cannot implicity string to label

[kidpro]

i want to show my result on a lable which i want to use in a method of book class

class Book
{
Form1 newform = new Form1();
public string BookTitle;
public string BookAuthor;
public string PublishDate;
public const string Publisher = "MICROSOFT";
 

public void GetDetails()
{
// showing error here cannot implicity string to lable
newform.lbl_view_title = this.BookTitle;
}
 
}
private void btnMain_Click(object sender, EventArgs e)
{
 
CSharp.BookTitle = textBox1.Text;
CSharp.BookAuthor = textBox2.Text;
CSharp.PublishDate = textBox3.Text;
 

CSharp.GetDetails();
}