Here I have created sample that will help you out.
HTML
<asp:GridView ID="gvLinks" runat="server" OnRowDataBound="RowDataBound" AutoGenerateColumns="false">
<Columns>
<asp:TemplateField>
<ItemTemplate>
<a runat="server" id='followuser' data-id='<%# Eval("UserId")%>'> Follow</a>
</ItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>
Code
protected void Page_Load(object sender, EventArgs e)
{
if (!this.IsPostBack)
{
DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[1] { new DataColumn("UserId", typeof(int)) });
dt.Rows.Add(1);
dt.Rows.Add(2);
dt.Rows.Add(3);
dt.Rows.Add(4);
gvLinks.DataSource = dt;
gvLinks.DataBind();
}
}
protected void RowDataBound(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
HtmlAnchor anchor = (HtmlAnchor)e.Row.FindControl("followuser");
anchor.Attributes.Add("class", "fa fa-twitter");
string text = anchor.InnerHtml;
anchor.InnerHtml = "<i class='fa fa-twitter'></i> " + text;
}
}
I hope this will help you out.