Wiring for ceiling fan question.
If you only have one switch on the wall, and only a black and white wire at the box, then you can only power the whole fan and light from there, you cannot dim the light without dimming the fan.
If you keep with a fan with a remote, you can just use the remote to dim the light seperatly, leaving the fan on full power. Otherwise, you will need to replace the 2 wire cable with 3 wire cable, allowing you to have control over the fan and light seperatly.
Put some pictures up of the box, the switch, and the new fan and we can help more.