How do I get JAVA and opera Mini5 onto my F900?

I have not had my Acer F900 for long so I hope you will excuse what might me a silly question

Looked at the reviews and speed trials of the various browsers and Opera min5 (beta) seemed to come out best so I tried to install it on my F900 phone

Followint the instructions on the Opera web site tried to download from explorer direct onto my phone but it only downloaded 1K.....
so that did not work

Downloaded it to the hard drive on my computer and hence to the F900 and I have the JAR file of 220k in my memory card

Double clicked on it to install and it came back saying ;no application associated with this file; which I assume is Microsofts rubbish error message for Java is not installed on this phone

Can anyone with an F900 phone help me to get Opera installed

Appreciate anything...............

HELP!

Pete