How can I use the ashes from my out door fire pit. In the garden ?

Here are some uses for ashes - https://www.thisoldhouse.com/ideas/10-uses-wood-ashes - good luck

great compost for the garden

I have used charcoal ash as a fertilizer an bug deterient. Those pesky little white almost transparent natty things you get on roses and vegetable plants. I take the cooled charcoal ash and lightly sprinkle directly on plants. This way I don't have to use store pest control or fertilizer. Has always worked amazing for me.