First, get a copy of form 16 (Part B )and 12 month pay slips 

(i)Salary arrears 
The gross salary as in point 1(a) already contains the salary arrears .......
The gross is basically sum total of; 
(a)basic salary , 
(b)exempt allowances( Washing, transport etc )
(c) non exempt allowances ( DA etc ) ,
(d)perquisites and
(e)profits in lieu of salary

Now, first figure out the exempt allowances portion u/s 10 ...
Then, figure out the 12 month basic(alone) from payslips ...

Subtract from gross the basic and exempt allowances( mentioned in form 16 ) to arrive at non exempt allowances ...(THIS FIGURE WOULD CONTAIN THE ARREARS NON EXEMPT PORTION )

(ii)Bonus - The bonus would appear in form 16 under heading" profits in lieu of salary" ...if It does, then put it under same head in return .

if it does not reflect any figure i.e shows 0 , then it is already covered in gross 

(iii)likewise for perquisites ...if perquisites are mentioned , then mention it under perquisites else it is taken care of in gross ...No need to worry separately)

(iv) Check for deductions under section 16 i.e tax on employment and entertainment allowance 

Now, salary + non exempt + perquisites + bonus - deductions
(This would cover your arrears , bonus and be the final figure from salary that is subject to tax)