I think Septimia is right - the readings may well have been chosen so you will need to know what it is so you can practise it first.
Is it a religious funeral so you could choose a passage from the Bible? If not, there are plenty to choose from online.
Do not Stand at my Grave and Weep
Bilbo's Last Song (At the Grey Havens)
Crossing the Bar
It would be unusual for someone to be asked to do a eulogy if they were not really close to someone. If it is a eulogy, can you think of any happy times you remember with your uncle when you were young, even an amusing anecdote too? Or ask your siblings to help you write it.
Your aunt would need to see and approve first.