Hi @shaniqua,
I'd suggest you check out @Noelle's guide on How to fill a raised garden bed and How do you fill a raised garden bed as they provide the guidance you are looking for.
For planting, herbs are an excellent place to start because they are forgiving and grow quickly. Basil, parsley, chives, coriander and rosemary all perform well in raised beds. Leafy vegetables such as lettuce, rocket, silverbeet and spinach are simple and fast growing, while cherry tomatoes, beans, peas and capsicums are also reliable choices once the weather is warm enough.
For your lemon trees, choose a sunny position with well-drained soil. Regular watering and feeding with a citrus-specific fertiliser will encourage healthy growth and fruiting. Lemon trees can be planted in the ground or in large pots if space is limited.
Avocado trees also need full sun and excellent drainage, as they dislike wet feet. Plant them in a well-prepared area away from waterlogged soil, and mulch well to protect the roots and maintain soil moisture. Young avocado trees benefit from shelter from strong winds and extreme heat while they establish, so installing a Tree Guard Sleeve would be beneficial.
Let me know what you think and if you have further questions, please don't hesitate to reach out.
Jacob
