Dear Priyanka,
It seems from your post that you are in a tricky situation. Since you are already three months in the company, by now you must be well aware of the organizational structure. Firstly, you should have all the information regarding each and every employee (like DOJ, designation, promotion, transfer, last increment given, etc.) working in the organization along with their respective departments. Next is to find out the salary and wages of each and every employee along with their grades and scales (if any). Now, since you are not a compensation and benefit management specialist, the best and easiest possible way to build a salary structure is to compare the salary structure of similar industries and build one of your own. Of course, in this case also, you have to at least know the basic things of building a salary structure (like building grades and scales, increment time span and amounts, promotion fitments, Evaluation Bar, etc.). Finally, you can create a wage matrix of your own as per the requirements of your company and get it validated by the top management.
Regards,
Awvik