Drag the TextBox, Label and button from your visual toolbox to your winform, then design a simple UI that allows you to copy file from another folder in c# as shown below.

Add code to handle the Browse button click event allows you to select the file you want to copy.
private void btnBrowse_Click(object sender, EventArgs e)
{
using (OpenFileDialog ofd = new OpenFileDialog() { Filter = "All|*.*" })
{
if (ofd.ShowDialog() == DialogResult.OK)
txtFileName.Text = ofd.FileName;
}
}
Add code the handle the Copy button click event allows you to copy the file to another directory.
private void btnCopy_Click(object sender, EventArgs e)
{
using (FolderBrowserDialog ofd = new FolderBrowserDialog())
{
if (ofd.ShowDialog() == DialogResult.OK)
{
FileInfo fileInfo = new FileInfo(txtFileName.Text);
txtTargetPath.Text = Path.Combine(ofd.SelectedPath, fileInfo.Name);
File.Copy(txtFileName.Text, txtTargetPath.Text, true);
MessageBox.Show("You have been succesfully copied.", "Message", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
}
}
Press F5 to run your application, then select the file and target directory to copy.