From the Bee Garden Earthwork (East) the footpath north north west through the wood is fine, but then the track across the openland is not obvious on the ground – just head towards the huge electricity pylon in the distance, and you’ll pick up one of the main footpaths again, from about SU992643.
Otherwise from the car park at SU993635 (on the west side of the road that goes from Stonehill Road across the west edge of the common) latch onto the wide footpath from SU990638 and follow the map to the barrow.
The barrow is a Scheduled Ancient Monument (no 20145) and has heavy-ish vegetation over most of it, but a path goes straight over the top of it. It’s about 30m in diameter. The pdf document via the link below gives more info about measurements.