read -p 'username : ' usr_value
read -sp 'password : ' psw_value
echo
a=fghj
if["usr_value" = "$a"]  #I am having problem in this line
   then
     echo "you have correct username"
   else
     echo "you have incorrect username"
if

if [ <condition> ] #mind the whitespaces

if [ "usr_value" = "$a" ]