Basically, I am going to guide you on how to create your very own spell.
First, you're going to have to state what you want to happen. Do you need a job or money, or you want to attract a new lover? Just be specific on what you want the spell to do, if you're not clear on your intention, then there is a high chance of your spell not working. You might want to relax a bit before you do this, get a bath, meditate, do whatever relaxes your mind. You don't want to set your intention when you have thoughts running through your mind.
Now that you have set your intention for the spell, you need to think about what materials you will need for your spell. It is entirely up to you, you can use candles, herbs, stones, crystals, incense and so on. It is best to choose materials that have a connection to your intention. An example would be choosing a red candle for a love spell.
Timing is really important. In many Traditions the moon phase are very crucial, while with others it's not even significant. Positive outcomes are usually cast on a waning moon. Anything negative is best to cast on a waning phase, it really depends.
Some people only do spells on a certain day, for example you may wake up one morning and feel that today feels like the best day to cast your spell. If you're a very confident practitioner you may want to cast a spell without even timing it. To me, it really depends on the individual.
How to cast it
Are you going to chant the spell or just call upon the gods you work with? It really only matters what you think is best, you don't have to say anything verbally, you can do it like a wish, visualizing your spell working. It doesn't matter how you cast it just as long as you have done it. You can even cast it out by using a poem.
Use all these steps as a guide and you will eventually be able to write your own spell.