try this or follow this ....
string str="insert into tablename (column1,column2,column3,column4,column5,column6,column7)values('"+txt1+"','"+txt2.text+"','"+txt3.text+"','"+txt.text+"','"+txt.text+"','"+txt.text+"'"
sqlcommmnad cmd=new sql command(str,con);
cmd.exicutenonquery();
con. close();