converting integert to date format

Question

Hi

 

i have month and year like

int lastpaidyear = Convert.ToInt32(lastpaidmonth.Rows[0][1].ToString()); ex:8

int lastpaismonth = Convert.ToInt32(lastpaidmonth.Rows[0][2].ToString());ex:2012

 and 

int selectmonth = Convert.ToInt32( ddlmonth.SelectedValue.ToString());ex:10

int selectyear = Convert.ToInt32( ddlyear.SelectedValue.ToString());ex:2015

now i want total month ?

 

please help me