search box -> I need to concat first name and last name from one table and join it to a 2nd and return item from 2nd table

search box -> I need to concat first name and last name from one table and
join it to a 2nd and return item from 2nd table

So the search would be like 'Ozzie Smith'
First table has (username, fname, lname) = osmith, ozzie, smith
Second table has (username, team) = osmith, cardinals
I need to concat the first and last name columns from the first table join
it by username on the second table and return the team name.
I have been trying and trying...brain melted. I need your help!
Thanks!