Okay, just wondering, the pitch for a soprano/descant is from C (1 octave above middle C) to the D right beneath the third ledger line, right? But it sounds an octave higher. And when I notate it on Sibelius, it has a treble clef with an 8 above it. That just means it sounds an octave higher, right? Any help would be GREAT!

Technically yes. But most experienced recorder players will do fine if you just note that the line is to played by descant/soprano. Likewise, you will often see a little 8 below the clef for tenor recorder. Whether it is there or not, simply notating that the line should played by tenor is all that a recorder player needs.

With alto, things can get more interesting because some older printed music puts the alto line an octave down with the expectation that the player will play it an octave up. So alto players must be ready to play the notes at pitch or play an octave up as the situation requires.

The F bass (or basset as some people refer to it) has its notes written an octave below actual pitch. Again, one might or might not see a little 8 above the bass clef.

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Edit ...
I should clarify the comment about the 8 below the clef for tenor: Although the tenor plays at pitch, one sees the 8 sometimes when playing music originally written for vocal use.

Whatever the case, 8 or no 8, recorder players will know what to do if you specify the instrument you want used.