@mim this is a spiritual practice.
There are many techniques one can use but here i will give one example:

if let’s say you want more money or better health - the desire can be anything, you can say affirmations in your mind as if the thing you want is already true. for example “I have the best health in the world” or “I always have more money than I need”.
As you continue this practice it will be normalized in your mind and you will believe it more and more. The belief makes the subconscious mind manifest it in the external world in one way or another.

When you succeed in manifesting things, your faith will grow and it will eventually become easier as the mind will more easily pick it up, when one has faith in what he/she is saying to him/herself.