If you've got the kit with the flexible rod, two lots of felt doh dah's, the blue paste and the grease, then here goes.
First, push the rod down the barrel, from the muzzle end, until it is at the opening of the breech, just. I usually then back it iff a fraction, as I do not want to shove blue paste down the transfer port ( pcp).
That done screw an abrasive felt pad on the end, and cover it in blue paste. Not too much, as it just squishes off onto the muzzle. Feed the whole thing into the barrel, and just scrub the first 6 to 8 inches of the barrel. I usually scrub about 20 times.
Pull the rod out, unscrew and bin the now black felt pad. Put on a plain felt pad, cover it in grease, and do the same again. Remove the felt pad and put another plain felt on, with NO grease. Same again. Then repeat the last step.
Try some groups. Sometimes the barrel needs to have 20 or so shots through before it comes back on song, sometimes not.
Hope that makes sense!
Neil