Setting the format as 0000 (i.e. it must have 4 characters) is different
than specifying the number of decimal places. If you need to have a number
that shows up as 0714 rather than 714, the only reason it would be doing
that in the first place is because you have your data type set to Number
instead of Text. Number data types should only ever be used when you're
going to calculate using this field.
If you want to do this in the code, the Help file "Format Property - Number
and Currency Data Types" will tell you everything you need to know about it.
If you can do this in your table (if what you're trying to format is a
stored value and not one that's calculated), go to the Design view of your
table, click on the correct field, and look at the window at the bottom of
the screen. Here you can choose Format, decimal places, and other items
with the dropdown arrows (which show up when you click there).