What Cat said.
If you're a smoker, try and stop.
In the colposcopy they 'paint' the cervix with a liquid that shows up any irregular patches of cells. If they see these, they may take a biopsy (it's just like a harsh little prick). You may have light bleeding for 24-48 hours afterwards (though I didn't). Depending on the result, you'll either be called in for another smear or colposcopy in 6 or 12 months, or they give you some treatment (laser/cauterisation).
For now, it's nothing to worry about.