<-- that is a picture of lumbridge.
Step 1:Now,Use your home teleport or just walk in front of the castle you see nows, front door.
Step 2:Walk to the castles front gate
Step 3: Go to the general store with the pot then the next house to the left.
Step 4: Talk to the explorer.
Another version:
Use the world map and walk towards the green star!!!
xxxsparklycrystalxxx
Explorer Jack is found a few squares south-west of the training area in Lumbridge.
There are several NPCs called "Jack". One of them is "Explorer Jack", which you can find north of Lumbridge Castle.
You need to complete the Lumbridge/Draynor Achievment Diary. This can be started by speaking to Explorer Jack.
You simply need to return to Lumbridge and talk to him again about Myths of the White Lands.
He is in a building near the general store in Lumbridge. The building that he is in is indicated by the green star that is over it on the minimap.
Go talk to Explorer Jack in lumbridge. You will then be able to start the medium achivement diary. Complete all the tasks. Then go back and speak to Jack and he will award you with a Level 2 explorer ring.
After you have retrieved the "Enchanted stones", all you need to do is speak to Explorer Jack in Lumbridge and give him the stones.
Explorer Jack can be found next to Lumbridge General Store.
To beat jack on runescape, you need to slide on the ice and bump into him.
Runescape works on both Firefox and Explorer. You have to download Java in order for it to work on either though.
look on this link
I don't think there is a character with that name.