Check Engine Light - P0446 / 0903 - EVAP issue

[MaxSE97]

My first post here...hoping y'all will prove me right with regards to this forum.

My '97 Maxima's check engine light has been on since I took ownership. I started with four different error codes, but have managed to whittle it down to only one. When I check it myself by counting the flashing dashboard light blinking, the remaining code is 0903. The Autozone guy pulled a P0446. Either way, it's something to do with a purge or vent solenoid, or vapor canister. When I park the car in the garage, I can definitely smell gas.

Can someone please help me identify the possible culprit? Are the purge solenoid and vent solenoid two different parts? Searching on multiple sites, I've been able to identify a couple of items that I'm hoping you can help me with. Easiest for me to describe is to look at Autozone's site and search these two parts for my vehicle: "Vapor Canister Shutoff Valve", and "Canister Purge Valve Solenoid". The first one, based on the picture, is located behind the driver side rear wheel well. The latter, I haven't found yet on my car, but I'm guessing it's under the hood somewhere. Can someone please help me locate it?

Are both of these parts reasonable places to try to clear the check engine light? Feels like a dumb question, but is the vapor canister the same thing as the EVAP canister? What are the actual functions of the purge and vent valves?