How to customize tally software?

My father has recently purchased Tally ERP 9 software in his town. After purchasing, we realized that the Tally software needs lot of customization. I personally tried, and did some customization. But, could not do all. Like we need to have Sale Invoice in one particular format, where in I was not able to get few columns like MRP of product, Discount column and there were lot of formatiing and other issues. If I get some solution, I can share my full requirement. Or if you can advise me on some source where I can get all such queries answered. What is best way to solve such issues? Please help.