Help me create a button to generate an ascending sequential reference number on a worksheet

[Blue Owl]

I have no VB skills and this is an urgent query I have.I have a spreadsheet with first column as Request ID, first free row is A2.
I need a button that will generate a number as a reference to a new request in a log/register.
It needs to insert on a new line at the top of the spreadsheet in A2 each time.
Format of Unique Reference needs to be: DSR0000001 then DSR0000002 and so on.
Please can you detail a step-by-step solution (I have no programming skills).


Thanks