Having an odd problem with my old school fuji. It wont stay in the lower gears, it tends to shift up out of them back towards the middle of the cluster. I checked park tool and sheldon brown's sites but I'm not sure what I should be adjusting.

There is probably a screw or bolt that holds the shifter in place on it's mount. Tighening the bolt increases friction and holds the shifter in position against the spring tension in the derailers.

In the centre of the drum for the shift lever will be an adjustment screw. This screw adjusts the friction on the lever assembly and holds the lever assembly together. Tightening it should prevent the slippage, but will require some experimentation to obtain a setting that provides smooth lever movement and balances the rear derailleur's return spring.

This bolt usually had a ring or wings on the head so you could tighten it if necessary while riding along. Lubrication of the shift lever pivot could also cause unwanted shifts to the smaller cogs to happen.

Sometimes the ring may switch from friction to indexing mode. Simpler levers use the ring just to tighten the lever.
Consider dismantling and cleaning the lever. Note the order and position of the various washers and DO NOT LUBE the friction washers.

Thanks guys, I will try tightening the shifter itself.

It could be shot, they do wear out after awhile (if tightening doesnt work)

That worked like a charm. thanks for the help.