There are a few ways to adjust the trigger on a Tikka T3. One is to use the adjustment screw on the trigger itself.
This screw can be turned in or out to change the pull weight of the trigger.
Another way is to remove the stock and use a hex key to adjust the screw located at the back of the trigger assembly. This will also change the pull weight.
Finally, some triggers come with a spring adjustment tool that can be used to adjust the pull weight.