Sometimes it's really easy to change out spark plugs and sometimes changing the spark plugs out on certain vehicles can be really hard because they're tucked away under a bunch of stuff.
Vehicles like a truck usually have the spark plugs easily accessible while some cars you have to actually put the car on a lift and get to the spark plugs underneath the vehicle.
When changing spark plugs though sometimes you need to replace the spark plug wires along with the spark plugs because sometimes the spark plug wire boots will be stuck on the spark plugs.
If I knew what make and model of vehicle you have I could tell you exactly how hard or how easy it is to change the spark plugs.
The changing the spark plugs is usually the easy part as long as you can easily access them but if you can't access the spark plugs easy enough then it can be hard and you may need a shop to change them for you.