I am a football (soccer) player and an occasional hiker. I am also a relatively new gardener and some of the works demand a lot from upper body strength. It seems to me that my upper body is really thin compared to my thigh (basically the entire upper body, from shoulder to waist). I have a rather small skeleton in my opinion. Is there any effective way to train my whole upper body to grow bigger and stronger at the same time? If it is not possible, which part of my upper body should I train first? (e.g. chest). I rarely go to a gym or do weight bearing exercise on my own.
You should definitely do the big compound movements. Deadlifts, Bench press, Shoulder press (standing). Doing shoulder press while standing will add that you'll be contracting your core to stabalize, making it an exercise that works your shoulders, arms and entire core. You can also do pull-ups and/or bend-over rows for your back. If you feel like your upper body has caught up to your legs you can add squats to the mix.
Hit them hard and heavy for 5 sets of 5 reps. You can add some isolation movements to target your arms like diffirent variations of bicep curls and tricep extensions.
Don't forget to eat enough and take ample rest because your body will need it when doing this type of exercising, especially combined with playing football.