How to use the divide function in the query?

Assuming all of these columns are int, then the first thing to sort out is converting one or more of them to a better data type - int division performs truncation, so anything less than 100% would give you a result of 0:

select (100.0 * (SPGI09_EARLY_OVER_T – SPGI09_OVER_WK_EARLY_ADJUST_T)) / (SPGI09_EARLY_OVER_T + SPGR99_LATE_CM_T  + SPGR99_ON_TIME_Q)from CSPGI09_OVERSHIPMENT 

Here, I've mutiplied one of the numbers by 100.0 which will force the result of the calculation to be done with floats rather than ints. By choosing 100, I'm also getting it ready to be treated as a %.

I was also a little confused by your bracketing - I think I've got it correct - but you had brackets around single values, and then in other places you had a mix of operators (- and /) at the same level, and so were relying on the precedence rules to define which operator applied first.

Try something like this

select Cast((SPGI09_EARLY_OVER_T – (SPGI09_OVER_WK_EARLY_ADJUST_T) / (SPGI09_EARLY_OVER_T + SPGR99_LATE_CM_T  + SPGR99_ON_TIME_Q)) as varchar(20) + '%' as percentageAmountfrom CSPGI09_OVERSHIPMENT

I presume the value is a representation in percentage - if not convert it to a valid percentage total, then add the % sign and convert the column to varchar.