i dont have picture messaging enabled on my BB account but as far as I know:
Either A - go to messages, click menu, click compose MMS, select contact, type subject line click menu, pick add picture, select picture, send

Or B - browse pictures, open correct one, click menu, click send as mms, select contact, add subject, send.

This is from the 4.6 software on my bold so the 4.5 on the pearl might be slightly different but hopefully that's enough to get you on the way.
(bill, Sun 7 Jun 2009, 20:15, 3 replies, latest was 16 years ago)

Not possible sadly
and BT wont help as it's an orange phone that I had cracked :(
( fuck shit up the best you never had, Sun 7 Jun 2009, 20:21, Reply)

Does it fail on sending
and end up with a red cross in the message list instead of a tick or something else?
(bill, Mon 8 Jun 2009, 0:40, Reply)

or c
send an email, picture messaging is for the Japanese.
(PsychoChomp, Sun 7 Jun 2009, 21:44, Reply)

But the person in question can't receive emails on their phone
Not my fault they're rubbish.
( fuck shit up the best you never had, Sun 7 Jun 2009, 21:46, Reply)

I don't know how you could be friends with such a person.

(PsychoChomp, Sun 7 Jun 2009, 22:33, Reply)

The person is clearly crap.

( thealternativefact, Sun 7 Jun 2009, 22:34, Reply)

indeed

( fuck shit up the best you never had, Sun 7 Jun 2009, 23:28, Reply)

That
works on my Pearl 8110 with the v4.5 software.

Maybe it's just a case of finding BT's MMS gateway details and changing the settings.
( rubberduck should only be used after consulting with your GP, Mon 8 Jun 2009, 7:12, Reply)