Click your instrument and select your grade using the list at the link. I would suggest the following.
Wind Ensemble- Grade 1 (advanced-medium), Grade 2 (medium-easy)
Symphonic Band- Grade 2 or Grade 1 if you are feel ready
Concert Band- Grade 2 or Grade 3 (easy/very easy)
When you find a solo or ensemble you find interesting use Youtube to find a recording.
Once you find one you want to perform order it online at www.jwpepper.com or any online music store. Solos cost on average about $10.
Let me know if you have any questions or if you want to talk through a solo you might want to buy. I can let you know if it is an appropriate level of difficulty for you. I would HIGHLY suggest checking with me before you select one.