Creating usernames in excel

I am trying to create specific usernames in excel by combining first name and last name columns but i also need to add other information to the created username. For example if the first name was Jimmy and the last name was Rogers but i needed the username to be jimmy.rogers@test (i.e. adding a fullstop/period between the first and last name and the @ symbol after the surname followed by the word test, what is the best way to do this? Any help would be appreciated.

I have tried the concatenate function but have only combined first name and last name

No need to overcomplicate things. There are two simple ways. Use the functions below

1. =LOWER( A1 & "." & B1 & "@test" )
2. =LOWER( CONCAT( A1, ".", B1, "@test" ) ) if older version =LOWER( CONCATENATE( A1, ".", B1, "@test" ) )

results

Whith these you can do this simply