Getting fit & gym. To get married?

I want join Gym. My age is 26, male. I have got medium slim body. I met with a small accident in that my collar bone was broken. Still it is in broken state. I didn't go to any operation as I didn't have any problem with that. Its been almost more than 5 years since that accident happened, means it happened when I was 21 age. Now I have got belly fat & my arms are small. I am getting married after 6 months. So I want reduce my belly fat & increase my arms size. So I'm planning to join gym. So, will my collar bone accident, will it be affected if I join gym? How to reduce belly fat considering I got 6 months to get married? I want increase my arms size so, what you suggest me about joining gym considering as I met with that collar bone accident. Now I'm not having any pains regards that fracture & even in last 5 years I didn't face any problem regarding that collar bone fracture. So please suggest me about getting fit considering my case. Thanks in advance.