new to the board nedding some advice please

this is my first post so sorry if it sounds a bit all over the place ,thanks
hey ppl im 21 years old and have recently started to become very intrested in improving my body and health. i weigh 13 stone and am 6ft tall.i am looking to turn small fat deposits around the chest area and stomach area into muscle aswell as building my arms back and shoulders.i eat healthy and at the mo am training around 4-5 days per week.i am really beggining to enjoy the efects and notice the diffrence.the problem i seem to have is that i am very weak in the arms.when it comes to squats and sit ups im fine but my arms are very weak and i can only lift light weights any ideas on how to increase strength and also burn and tone the fat around the chest and belly. thanks guys