Milan,

It is on O2 in the UK (as that is the SP I have I can't comment on
other SP's)

Go to message > new multi media message

The on "To:" enter the e-mail address

Write your multi media message as normal and insert pictures / files
as normal.

Send

That's all there is to it.

It then comes as an e-mail to the recipient.  The text you typed and
the picture / file you sent come as an attachment.

The "From:" e-mail address is shown as:

+441234567@mediamessaging.o2.co.uk

Where 1234567 is your telephone number.  The +44 relates to your
country code (+44 for the UK)

Hope that helps!

Casper.