I would advise you to post this job in our gardening category. We have categories for both a garden wall and also stone/concrete paving and brick/block paving.
When posting your job, we will prompt you to explain that you're just looking for a quote at this stage. I would also recommend reiterating this in your job description too to make it doubly clear as tradespeople pay for job leads.
I hope this helps.
The Ask an Expert Team