After some works I finnaly do what I need with this code:

/************************/

void fill_tree()
        {
            DataSet ds = data_set("SELECT * FROM Information_Schema.tables ORDER BY table_name");

            TreeView1.Nodes.Clear();

            foreach (DataRow dr in ds.Tables[0].Rows)
            {
                TreeNode parent = new TreeNode();

                parent.Text = dr["TABLE_NAME"].ToString();
                parent.PopulateOnDemand = true;
                parent.ToolTip = "Click para obter as colunas";
                parent.SelectAction = TreeNodeSelectAction.SelectExpand;
                parent.Expand();
                parent.Collapse();
                TreeView1.Nodes.Add(parent);

                DataSet dstwo = data_set("SELECT * FROM information_schema.columns WHERE table_name LIKE '" + dr["TABLE_NAME"].ToString() + "' ORDER BY column_name");

                foreach (DataRow drtwo in dstwo.Tables[0].Rows)
                {

                    TreeNode child = new TreeNode();

                    child.Text = drtwo["column_name"].ToString();
                    child.PopulateOnDemand = true;
                    parent.ChildNodes.Add(child);
                }

            }
        }

/************************/

But not I had another question, I want to click on one parent node and show the rows of that table in a grid view.

My problem is how to make the node clickable to call a function or something like that.

About his, I have now two modules, one with a form to create new nodes, and other only with the treeview.
My question is, can I refresh the treeview by click on the button from the form?