h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

can anyone help me with a Latin translation for 'quietly confident'

This needs a pronoun which changes depending on who is confident and who is saying it. Speaking of a third party who is confident one uses

"quiete sibi confidens"="quietly confident in himself/oneself"

but speaking of oneself one uses

"quiete mihi confidens"="quietly confident in myself"

and for a second party

"quiete tibi confidens"="quietly confident in yourself"

I have not included the plural forms.

i was looking for a ingenious motto for our football team

Since it's a team, you need one of either:

'quiete nobis confidentes' = 'quietly confident (in ourselves)'

or

'quiete sibi confidentes' = 'quietly confident (in themselves)'