fengyuanfei, The entire Squamish River system has over 30 miles of fishable water. Some can be accessed by foot, while other areas can only be reached with a boat. A map of the Squamish region will show you some access points and one can easily discover more from there.
The fishery between now and April (before the freshet starts) is catch and release only. There are four species of fish that can be targeted and found - Bull trout, cutthroat trout, rainbow trout and steelhead. Bull trout are most abundant among the four and can be caught by using presentations that resemble their feed at a given time. The diet of bull trout switches from salmon eggs, flesh to fry as the season goes on. Rainbow trout and cutthroat trout can be caught at any given time but are harder to find due to their lower abundance and migratory behaviour. Steelhead fishing on the Squamish usually doesn't start until March, and the number is significantly lower than the Vedder River. Remember, catch and release applies to all four species so handle them with care when caught. I prefer to bring a catch and release net to minimize the damage.
You can either float fish with a drift rod, lure fish with a spinning rod or flyfish for all of these species. The gear used should suit the size of the species. The bull trout found in the Squamish River range between 2lb to 6lb, but some can be much bigger. The cutthroat trout and rainbow trout are generally between 12 inches to 18 inches in length, a 4 to 6 wt fly rod is adequate enough for these. The steelhead are much bigger than the above three species, a 6 to 8 wt fly rod or medium slow action drift rod is required.