How to get to Fishing Zone:
In Quest Tab>Global Teleports Select Skilling> Scroll Down and Click Fishing> Then Click Teleport
Once here Right click the Fishing Master and Select Pickpocket, This will open his shop.
How to Train Fishing:
1st Spot:
Net Level Needed 92 Fishing
Harpoon Level Needed 96 Fishing
2nd Spot:
Net Level Needed 62 Fishing
Harpoon Level Needed 76 Fishing
3rd Spot:
Cage Level Needed 40 Fishing
Harpoon Level Needed 35 Fishing
4th Spot:
Net Level Needed 16 Fishing
Harpoon Level Needed 35 Fishing
5th Spot:
Net Level Needed 1 Fishing
Bait Level Needed 5 Fishing
6th Spot:
Lure Level Needed 20 Fishing
Bait Level Needed 25 Fishing
7th Spot:
Net Level Needed 92 Fishing
Harpoon Level Needed 84 Fishing
8th Spot:
Net Level Needed 92 Fishing
Harpoon Level Needed 96 Fishing
To Catch Squid you will need the Captains Harpoon.
A Captains Harpoon Can be obtained by buying it here or from a player. It is also a random reward from Washed-up caskets which are obtained while fishing.