If you are not a developer, then you have a problem. The simplest way to achieve what you need would be to take an existing control (number.ftl for example) and customise it with javascript to acheive what you need. Whilst not that difficult, it may not be that straightforward because of the need to strip out commas when editing (assuming your underlying property definition is numeric). I am afraid I cannot provide a step by step non developer guide because I would have to write it to do it.
There is a fair bit on the internet about custom forms controls, but it is all targetted at developers.