Hi Stan,
The recorder is not a transposing instrument like the trumpet or clarinet.
If you are playing an alto recorder using alto fingering then it is in concert pitch (C=C, B=B etc). You can play with other instruments or with backing tracks with no need to transpose.
Altos are referred to as “in F” because the bottom note is F. This fingering is also used for the Basset and Sopranino recorder.
Soprano and Tenor recorders are referred to as “in C” because their bottom note is C. They use C fingering which is essentially the same but what is written and played as F on the Alto is written as played as a C.
Sorry this is not a great explanation. Please let me know if it doesn’t make sense and I will try to explain it more clearly!
Best wishes,
Karen.