A common topic for the short presentation (IELTS Speaking Part 2) is "describe an important festival in your country".
My advice is to look for a description of your festival on Wikipedia. Copy the best parts of the description and make small changes if necessary. As an example, I've copied a short description of Christmas from Wikipedia.
Describe a festival: Christmas
Christmas is an annual holiday that, in Christianity, commemorates the birth of Jesus Christ.
Popular customs of the holiday include gift-giving, music, an exchange of greeting cards, church celebrations, a special meal, and the display of various decorations; including Christmas trees, lights, nativity scenes, and holly. In addition, Father Christmas (known as Santa Claus in some areas) is a popular figure in many countries, associated with the bringing of gifts for children.
Over the Christmas period, people decorate their homes and exchange gifts. In some countries, children perform plays re-telling the events of the Nativity, or sing carols that reference the event. Christmas, along with Easter, is the period of highest annual church attendance.
A special Christmas family meal is an important part of the celebration for many, and what is served varies greatly from country to country. In England and countries influenced by its traditions, a standard Christmas meal includes turkey, potatoes, vegetables, sausages and gravy, followed by Christmas pudding, mince pies and fruit cake.