<<< i also want to use the phone to connect to the internet. >>>
Did you get any software with the phone? In particular, software to install the phone as a "Bluetooth Modem" in the PC. If not, you may be able to download appropriate modem drivers from the Sharp website.
<<< I want to know what equiptment i need to use and whether i need an isp account. >>>
You shouldn't need any additional hardware. If you intend to use a Dialup connection to the internet, you will need a "pay-as-you-go" ISP account. Obviously you cannot use a monthly package with a mobile phone. The cost of the phone calls is all that you pay.
The alternative is to use GPRS which is via your phone's network provider. This is an "always on" system where you pay for the amount of data transferred rather than the time online.