WinMo 6.5 GPRS Settings

[Guest meaton]

I have the settings for GPRS/MMS for my phone but for the life of me cannot get them working correctly. I'm with Tesco Mobile (o2). I have an Acer Tempo F900 HD with Windows Mobile 6.5. I have entered the settings but it still refuses to work! Could someone clearly explain how i can remove all the settings and start again step by step? Its doing my head in!

Thanks,

Michael