The basic thing is first ..your service provider should have the facility of MMS for it to be send to your mobile from net ( PC ) to mobile ..then there are lotsa sites on the net...
Other thing be really beaware while doing those suff from some unknown site if you are a prepaid user ....coz u will never know how much the services providers deduces the amount from your account on you prepaid connection..
Try this
*mms.start4all.com/
Enjoy life buddy !!!